Help Center

General Patent Information

What is a patent?

Legal Definition

A patent is a right granted to an individual or group (such as a corporation) which permits the grantee the ability to prevent others from making, using, or selling the invention described in the patent. A patent can be sold, or the grantee may give others permission to use the invention (generally in exchange for royalty payments).

There are three main types of patents: utility patents, design patents, and plant patents. Utility patents are patents on inventions which function in a new way or to provide a new result. A design patent, as its name implies, is a patent on the aesthetic design or ornamentation of something that already exists. A design patent is granted when the design in question does not change the functionality of the object, only gives it a novel appearance. Design patents primarily contain drawings. Plant patents are patents on types of plants that may be reproduced by grafts and cuttings. Note that patents related to genetic engineering of plants are normally considered utility patents. Utility patents are by far the most common type of patents, and are what people normally mean when they just say "patent".

A patent simply gives the owner grounds to prevent infringement through legal means. By itself, a patent cannot stop someone from making or using an invention; it simply gives the patent owner the right to take the person to court if they do.

What are the different pieces of a patent?

Patents have a fairly standard format. The top of the patent includes the name of the inventor, the entity to whom patent rights might be assigned (often an inventor assigns a patent to his employer if the invention was conceived as part of his work for that employer), the patent number, the date the patent application was filed, the date the patent issued, the classes and subclasses under which the patent was classified (for whatever classification system is used; normally the U.S. or European classification systems), and the classes the examiner searched when determining if the invention was novel.

The real substance of a patent consists of an abstract (a very brief summary of the invention), the claims (which legally determine exactly what the patent covers and what it does not), and a description. The description may contain several parts, including a section titled "FIELD OF THE INVENTION" (which puts the invention in context by briefly describing the field of technology or business to which the patent is applicable), the "BACKGROUND OF THE INVENTION" (which describes previous, similar inventions, and the problems which remained unresolved, setting the stage for why this invention is new and useful), the "SUMMARY OF THE INVENTION" (which then describes the current invention), the "BRIEF DESCRIPTION OF THE DRAWINGS" (which relates to drawings that are part of the patent), and the "DETAILED DESCRIPTION" (which can be extremely detailed, and talks about exactly how the invention works, refers to every diagram, and often attempts to broaden the scope of the patent by suggesting other ways that the invention could be used or implemented other than just what is presented in the figures).

Finally, near the top of the patent you will also see references to other patents, and sometimes some references that are not other patents (we refer to this as "non-patent literature"). These are the references that either were provided by the inventor (often as a result of a patent search), or found by the patent examiner. Ostensibly, they constitute the prior art closest to the current invention. (Hint - they can provide good leads for a patent search.)

What are Claims?

Claims are crucial, both for Validity and Clearance searches, and for writing your own patents. The Claims, and nothing else, are what determine exactly what material a patent covers. The BACKGROUND OF THE INVENTION may discuss all sorts of related technologies and inventions, and the DETAILED DESCRIPTION may suggest 101 different uses for, or implementations of, the invention. But, if it is not in the Claims, it doesn't count. (OK, that is a bit of an over-simplification due to the Doctrine of Equivalents and other legal issues, but if you understand those topics, you don't need to read this tutorial).

Patents have "independent claims" and "dependent claims". Dependent claims are those that refer back to a previous claim, and thereby may require that previous claim to be valid for themselves to be valid. For instance, let's use a fictitious bicycle patent. Claim 1 might read "A lighter, more aerodynamic design for a bicycle rim by using an oval cross-sectional shape". And Claim 2 might read "The rim of Claim 1 where the cross-sectional piece is formed from aluminum".

Thus, Claim 2 is dependent on Claim 1, because, as an extension of Claim 1, Claim 2 cannot exist without Claim 1. This is a very important concept in Validity searches, where it is a common strategy to attempt to invalidate mainly the independent claims, to potentially invalidate the dependent claims in the process.

When and how is a patent granted?

In the United States a utility patent is granted to the first inventor of a novel process, machine, article of manufacture, composition, or a "new use" of one of these. There is a three-part test which determines if an invention is patentable. The tests are:

  1. Is the invention useful? (This is a very easy criterion to satisfy - any use will suffice.)

  2. Is the invention novel? (The invention must be different in some way from previous inventions.)

  3. Is it "unobvious?" (This test is perhaps the most subjective. It is determined by asking the question "Would a person with ordinary skill in the area of the invention, and possessing complete knowledge of the prior art, consider that the invention provides new and unexpected results?")

Design patents are granted based on similar criteria. However, the invention, rather than being useful, must be ornamental, and cannot change the functionality of the item. Note that different countries have different laws. The United States operates under a "First to Invent" system, while most other countries use a "First to File" system.

Who was first?

Remember that we said a patent may be granted to the first person to invent something (at least, under the First to Invent system). But how do you know who was first? In the United States, when two or more Inventors claiming essentially the same invention file applications, a proceeding called an Interference is conducted to determine who the first inventor is. The first inventor must be able to prove his case with appropriate evidence like laboratory records, logbooks etc. Therefore, even if the person who filed later is found to have invented earlier, he would be considered the first inventor. This is where an extremely important concept in patents becomes important: the Priority Date. The priority date is the earliest date that the inventor can prove he conceived of an invention (it actually gets a bit more complicated than that, but that definition will suffice for our purposes).

How does an inventor prove when an invention was first conceived? Well, this can get complicated if an argument of priority dates goes to court. They might consider all kinds of evidence, including witness testimony, lab notebooks, etc. But for most purposes it is simpler than that.
In general, the priority date is going to be the date that the patent application was filed. But, there are exceptions (and they are not infrequent - so be sure to check). These exceptions occur in a variety of circumstances including if a provisional application (which is a simplified application, largely designed just to prove an earlier priority date) was filed before the actual application, if the invention was first patented in another country (the inventor then gets to claim the priority date from the application he filed in the other country, since that proves the invention was invented earlier), or if the patent is a family member stemming from a Continuation in Part or a Divisional Application (in which case the new application normally gets to claim the priority date of the parent document).

So, hunt around at the top of the patent a bit. If you see dates listed that pre-date the application, or if information is present which indicates a Continuation in Part or a Divisional Application, the priority date is probably not the application date. Never, ever, assume the date the patent was issued is the priority date. You will always be wrong.

Understanding how to determine the priority date is very important in Validity Searches, as only prior art that pre-dates the priority date of the patent in question is relevant.

When does a patent expire?

This is not necessarily a clear-cut issue, but it is very important to understand for some types of patent searches and licensing issues, so read carefully:

  1. U.S. Patents filed after June 8, 1995 expire 20 years from the date of filing.

  2. U.S. Patents filed prior to June 8, 1995 expire 17 years from the date of issue, or 20 years from the first non-provisional patent application in the family - whichever is later.

Number 2 is a mouthful there. When we say "the first non-provisional patent application in the family" what we really mean (most of the time) is just "the application." But, we have to put it that way to be accurate, because Continuations-in-Part muck things up (you'll hear about them later).
Knowing how to calculate the expiration dates of patents is extremely important when conducting Infringement searches, because you only need to worry about patents that have not expired (which are referred to as being "in force").

Correcting errors in a patent?

A request for correction of errors can be filed with the USPTO,

Correction before application is published

If a patent application has been assigned a projected publication date, the private side of PAIR can be used to submit corrections to the bibliographic information, instead of mailing in a request for a corrected filing receipt. The request for correction should be submitted more than twelve weeks before the application is published. In the private side of PAIR, the applicant should select the Publication Review button and then the Request Data Change button on the screen. The instructions will then appear with a data entry box in which the changes can be inserted. Once the change has been confirmed, the Transmit Request button should be selected and the information will be electronically sent to the USPTO. Applicant may only submit a request through PAIR to request correction of inventor information consistent with the inventor information reflected in the patent application file.

Note: Private PAIR is available to applicants who have a customer number associated with the correspondence address for an application and who have acquired the access software (Entrust Direct Software and a PKI certificate). To register with private PAIR, see

Correction after application is published

If a patent application publication has a USPTO error, the applicant can submit a request in writing which should include a copy of the patent application publication with the errors marked and identify the page and line number of the originally filed application where the information was correctly submitted. The request for correction to a patent application publication must be filed within two months from the date of the patent application publication. This period is not extendable.

Only errors that are material will be corrected. Examples of material errors are missing claims, missing pages of specification or missing pages of drawings. Errors in assignment information or missing assignment information, missing section headings or minor typographical errors will not be corrected by the USPTO.

Correction after patent is granted

When the printed patent does not correspond to the record in the USPTO, a certificate correcting a clerical error will be issued by the USPTO without any charge. These are mostly corrections of typographical errors made in printing. If the applicant makes the typographic error, a fee is charged for issuing a Certificate of Correction. Certificates of Correction are used to correct typographical errors and misspellings in patent grants and trademark registrations but cannot be used to add new matter. If the patentee wishes to disclaim one or more claims in his/her patent, a Disclaimer can be filed in the USPTO. If a patent is found to be defective in certain respects, the patentee can apply for a Reissue Patent. A reissue patent is issued to replace the original patent and is granted only for the balance of the unexpired period. New matter cannot be added in a reissue patent.

Patent Maintenance Fees

Utility patents are subject to maintenance fees that are required to maintain the patent in force.  See the following USPTO related links:

General Site Usage and Information

Advertising on This Site

How can I advertise on this site?

If you are interested in advertising on our site, contact us at, or you may advertise via Google AdWords (just use the site targeting function to select our site). You can sign up for AdWords here.

I saw an ad on the site I don't like. What can I do?

We plan on testing Google's AdSense program as a way to help support this site. Under the AdSense program, a site does not have complete control over the advertising that is displayed. Rather, Google picks ads in a context-sensitive manner and places that ad on the appropriate page in the site. That being said, we do have the ability to block certain ads or certain classes of ads. We want this site to be family-friendly, and we want it to be inventor-friendly.

Being inventor-friendly means screening out ads that try to take advantage of inventors by offering useless/fraudulent services. Some invention promotion companies are known for bilking inventors of their money and offering no real service in return. The FTC has even prosecuted some of these companies. We will not tolerate these companies advertising on our site, and we have already spent substantial time explaining this problem to Google and asking them to work with us in identifying and banning such companies. But, some such ads may still get through. If you see any such ads, or any ads that offend you for any reason, please send us the exact URL that the ad points to, because one way we can ban ads is by URL.


Linking to This Site

How should I link to this site?

If you would like to link to one of our patents, please link to the full-text pages (not the images). The reason for this is that the full text pages are static, and will always be accessible using the format shown in the examples below:

A link to US Patent 6,000,000 would look like this:

A link to US Application 20010000001 would look like this:

A link to a European Patent would look like this:

The images are sometimes created dynamically and may not be available except through the full-text page.

What about linking to PDFs?

For a variety of reasons, we would prefer that you not link directly to PDFs. If you link to the full-text page (see above), the PDF is still only a click away.

There are several reasons not to link to PDFs. First, PDFs may be LARGE. There are patents that are hundreds of pages long. In such a case, the PDF would be many megs. If the user really wants the PDF, that's fine and they can always click through to it. But, if the text would have served their purposes, getting the PDF is a lot of wasted downloading time. Second, for technical reasons we sometimes change the way our site handles the PDFs. The images we store take many TERABYTES (a terabyte is 1000 gigabytes) of disk space, and we are always on the lookout for ways to store our images more efficiently. This could conceivably mean that, due to programming changes, links to PDFs will not always be static, while the link structure of the full-text files will never change.


PDF Help

Can't Print or Save PDF

The inability to save, download, or print from Acrobat is normally due to the necessary controls being hidden by default. To change your settings so that the toolbar containing these controls is available:

On Windows systems using Internet Explorer or FireFox:

  1. Right click on the PDF and choose "Page Display Preferences."

  2. Go into the "Internet" option on the left hand menu.

  3. Uncheck "Display in Read Mode by default."

  4. Go to the “Documents” option in the left hand menu.

  5. Uncheck “Allow documents to hide menu bar, toolbars, and window controls.”

While we use PDF files on our site, the behavior of Acrobat is beyond our control. If the above steps do not fix your problem we would be happy to try to help if you send us detailed information on the steps you took, the result, what browser and version of Acrobat you are using, and screenshots. However, submitting your question to Acrobat technical support may also help and notifies them of bugs or UI issues in their software.

Downloading Acrobat Reader

Acrobat Reader is a free PDF viewing tool, and can be downloaded from the Adobe Reader download page or the Adobe Reader main page on You can also download Adobe Reader wherever you see the Get Adobe Reader icon.

Once the link or icon is selected, you will have to specify your language, operating system, and connection speed. Once you have completed these steps, the Adobe Reader software downloads and installs automatically on your system.

Acrobat Reader is free and if you do not have the latest version, we suggest upgrading. The latest version of Acrobat Reader can always be found at

Problems with downloading PDFs?

If you encounter any problems while downloading PDFs, here are a few tips for troubleshooting:

  1. Install latest version of Acrobat. The latest version of Acrobat Reader can be found on Adobe's website at

    • Once the link or icon is selected, you will have to specify your language, operating system, and connection speed. Once you have completed these steps, the Adobe Reader software downloads and installs automatically on your system. Before you install the latest version, ensure that your system meets Acrobat's latest requirements.

    • Please note that you should ideally do a clean installation of latest Acrobat Reader version. This means that you should not install a newer version on top of an older version. This is known to cause problems. Instead, first uninstall the older version, then install the newer version.

  2. Run Acrobat with no other applications running in the background and no other plugins running in your browser. Some applications that run in the background might cause problems when running together with Acrobat. If you try to download a PDF and get a 2kb file that won't open, this is almost certainly a plugin issue. Here is the technical explanation (you don't need to understand it, just close other plugins):

    • The fact that some PDF "helper" applications cause Adobe Acrobat to malfunction is a lack of proper standards compliance. RFC 1341 indicates that the Content-Type field in an HTTP header should be used to identify document types. RFC 3778 indicates that PDFs should be identified via the MIME Media Type "application/pdf". This implies that PDFs should not be identified by the presence of ".pdf" at the end of the filename, but rather should be identified by the MIME information send in the HTTP header.

    • However, when given a MIME type of "text/html" but an extension of ".pdf", some applications allow the extension to override the MIME type. This is not correct. The MIME type provided in the HTTP header should determine how the file is treated.

  3. Check the size of the document you are downloading. Ensure that the size of the document is reasonable. There might be problems downloading documents that are greater than 2Mb.

  4. Check whether document you are trying to download has non-English fonts. If there are non-English fonts . embedded or linked, the fonts may need to be downloaded and installed to view.

  5. If documents are not opening when viewing via the web, then from the Edit/Preferences/Options Menu, untick the box Display PDF in Browser.

Viewing FreePatentsOnline PDFs

FreePatentsOnline offers you patent PDFs. To view PDFs,

  1. Search for patents using any one of our search forms.

  2. From the results list, select the PDF icon next to the patent of your interest. You can also view the patent PDF from the full text page, by selecting the PDF icon in the page.

If you click on a PDF link, and cannot open the document, you may not have a PDF reader installed. In that case, you can download Acrobat Reader.

If you do have Acrobat installed (and a current version) and still have problems viewing PDFs, there are several other possible problems. Please see our other Help material on PDF problems here.


RSS Feeds

The web has grown to be one of the biggest source of information. But then, keeping abreast with all the latest happenings in your area of interest would not be easy. RSS feeds solve that problem for you - it allows you to stay informed by reporting to you the latest updates.

RSS stands for Really Simple Syndication or Rich Site Summary. Also called web feeds, RSS is a format for delivering web contents which are constantly updated. RSS feeds usually come in XML format.

RSS feeds help you to:

  • Get all the latest news right away without having to search the web.

  • Manage the flow of information.

  • Keep yourself updated by opting for RSS feeds in your area of interest. You do not even need to be online to read your updates.

FreePatentsOnline RSS Feeds

FreePatentsOnline provides RSS feeds for all recent US patents and patent applications. For your convenience, RSS feeds are listed by classes too.

You can select the link RSS feeds in "Other Services" (home page), to see the list of RSS feeds available.

Reading RSS feeds

Some browsers have built-in RSS readers (e.g. Internet Explorer 7, Firefox 2 etc.). If you have one of those browsers, you will be able to view RSS feeds directly in your browser.

IF your browser does not have a built in RSS reader, you would require a program called an Aggregator or Feed Reader to read them. An aggregator is an application that allows users to view and read RSS feeds. Once you have set up your aggregator or feed reader, it will scan your selected RSS feed sites regularly, collecting all the recent updates.

There are web based aggregators, which track and report feeds so that you can view them in your browser, any time you want. Common web based aggregators include:

There are desktop aggregators, which can be installed on your computer. They help you to gather and review your selected feeds in your computer itself. Some of the popular desktop aggregators are:

Viewing FreePatentsOnline feeds

Browsers with built in RSS Reader

If you have a browser that has built in RSS Reader, you can subscribe to an RSS Feed by:

  • Select the RSS Feed you would like to subscribe.

  • Details of the feed selected would be displayed as a web page.

  • The page displayed would ask where/how you want your feeds – on your desktop (specify a folder/bookmark) or on the web (you can select one of the web based applications - google, yahoo or blogline), and an option to subscribe to the feed

  • Specify how/where you want your feeds, and subscribe to the feed.

Any new updates in your selected area of interest would be available either in your desktop or in the web, according to your specification.

Browsers with no built in RSS Reader

If you have a browser with no built in RSS Reader, you will need an RSS reader or a feed aggregator to view RSS Feeds.

  • Download a RSS reader or a feed aggregator (from any of the links mentioned earlier).

  • From FreePatentsOnline home page, select RSS Feeds from "Other services".

  • Right click on an item listed in the RSS feeds page, and copy the link for the item.

  • Insert the URL of the RSS feed in the RSS reader.

Any new updates in your selected area of interest would be automatically updated in your feed reader.



Many email service providers and internet service providers have SPAM filters to keep out the unsolicited email. Due to the volume of users we have, sends a lot of email. This occasionally causes email service providers to interpret our emails as SPAM.

To make sure that you can receive our email, you can "whitelist" email from Whitelisting means that you set up your email software to accept incoming email from a specific email address or domain, overriding your mail service provider's SPAM filter. uses several email addresses for communication with users. Therefore, the most effective way to make sure that you receive our email is to whitelist the entire domain. Depending on the exact email service or program you are using, whitelisting a domain may be done by entering something like one of the following:



  • *

In the event that your email service or program cannot whitelist entire domains, we would suggest you add these individual addresses to your whitelist:

Since every email system is different we have included whitelisting instructions for a few popular email service providers below.

AOL (version 9.0 or higher)

In AOL, you can add the FreePatentsOnline address to the "People I Know" list. To add the address,

  • Copy the "from" address from the latest FreePatentsOnline mail. (or you can copy the addresses listed above).

  • Select the Mail menu and select Address Book.

  • In the pop up box, select Add.

  • Paste the copied address/type the address required in the Other email field.

  • Make the newly added address the "Primary email address" by checking the checkbox.

  • Select Save.

AOL (version 7.0 or 8.0)

  • Select Mail in the Menu on the top of the screen.

  • Select Mail Controls.

  • The Mail Control Screen would be displayed. Select Next.

  • Select Customize Mail Controls for this Screen Name and click Next.

AOL (version 8.0)

  • You can select "Allow email from all AOL members, email addresses and domains" (allows all emails).

  • Select Next until the Save button shows up at the bottom.

  • Select Save.

AOL (version 7.0)

  • In the exclusion and inclusion parameters, include the domain


You can ask Yahoo to filter mails from FreePatentsOnline to your inbox.

  • Open Yahoo mailbox.

  • Select Mail Options.

  • Select Filters.

  • Click Add Filter.

  • In the top row, labeled From Header, select contains from the pull down menu. Enter the FreePatentsOnline address in the text box next to the pull down menu. (you can either give a specific FreePatentsOnline email address or use or * to whitelist the domain).

  • Move down to the bottom where there is the option Move the message to. Select inbox from the pull down menu.

  • Select Add Filter button once again.


To whitelist us in Hotmail, you can add our email address to your Safe List. For that,

  • Access your Hotmail mailbox.

  • Select Options from the top right (next to Help).

  • Select Junk e-Mail Protection (the first link).

  • Select Safe List.

  • In the space provided, enter the FreePatentsOnline address (you can either enter a specific email address or use * or to whitelist the domain).

  • Select Add.

  • Ensure the safe list box has the address you entered, and select Ok.

You can also add the FreePatentsOnline email address to your contact list:

  • Open the most recent email from us.

  • Select the Save Address button (to the right in the line of options above the email).

  • Click Ok.


To ensure that you receive FreePatentsOnline mails in your inbox, you can add the FreePatentsOnline address to your contact list. And, If one of our mails has been moved to the spam folder, you can mark them Not Spam, to whitelist it.

  • Open the latest issue of the e-mail you want to whitelist.

  • There would be a few drop down options just after the date on the right hand side. Select Add sender to contact list.


  • Select contacts from the options on the left side of the Gmail Inbox.

  • Select Create Contact on the top menu.

  • Enter the FreePatentsOnline address in the primary email box.

  • Select Save.

If one of our mails has been by mistake moved to the spam folder, you can prevent it happening by:

  • Selecting the Spam link - to open the spam folder.

  • Open the wrongly filtered FreePatentsOnline mail.

  • Select the Not Spam button at the top of the email (right next to the delete forever).


In MSN, to whitelist our mails, you can add our mail addresses to your Safe List. This is how you do that:

  • Select Settings: Email | Junk e-mail (bottom left, just above Calendar).

  • From the E-mail settings screen, select Junk E-mail Guard.

  • Select Safe List.

  • Enter the FreePatentsOnline address (you can either enter a specific email address or use * or to whitelist the domain) in the text box provided for Add people to safe list.

  • Select Add.

Outlook 2003 or higher

If you are using Outlook 2003 or higher for your emails, you can whitelist by:

  • Open the email.

  • From the list of emails, right click on the sender's email address.

  • Select Add sender to Address book.

  • Click Save and close.

For domain whitelisting,

  • Open email.

  • Select the drop down arrow after Contacts in the contacts section (left-hand side, below Folders).

  • Select New Contact.

  • In the E-mail addresses box, enter *

  • Select Add and click OK.

Norton AntiSpam

AntiSpam works along with Outlook, Outlook Express, Netscape and Yahoo, MSN/Hotmail to block spam mails before it reaches your inbox. To make sure FreePatentsOnline mails reach you, you can add us to your Personal Friends list or Global Friends list. Here is how you can do that:

  • Start Norton AntiSpam, select Status & Settings tab.

  • Select AntiSpam.

  • Select Configure button - right hand side bottom of the screen.

  • Select Allowed List tab - second tab on the list of tabs.

  • Select Add.

  • Enter FreePatentsOnline address in the Email address box.

  • Select Ok.

McAfee Spamkiller

The McAfee Spamkiller works with Outlook, Outlook Express, Outlook 98, MSN/Hotmail to block spams. To whitelist FreePatentsOnline mails,

  • Select Friends tab.

  • Select Email Address tab.

  • Select the down arrow to view Personal Friends List.

  • Select Add a Friend from the right hand side.

  • In the address box, add the FreePatentsOnline address (the specific email address), and select Single e-mail address as type, and Add.

  • Select Domains.

  • In the address box, enter, choose "all users at domain" as type and click Add.

  • Select Save.

Spam Assassin

In Spam Assassin, you can whitelist FreePatentsOnline in the User Preferences. To whitelist,

  • Find the spamassassin folder from your hard drive, and open it.

  • There would be a file named user_prefs. Open it with a text editor (for e.g. Notepad). If there is no such file, create it, instructions are available at

  • Make a new line in the file. On that line, enter whitelist_from, followed by the FreePatentsOnline address that you wish to whitelist. To whitelist the domain, enter

  • Save and close the file.

Help on Account Functions


Alerts are saved searches which are scheduled to run at specified intervals, and to then report matching documents to you, in the manner you choose. Alert notifications can be sent to you via email, in your account (via the "My Alert"), or both.

For your convenience, alerts are automatically run with a date range (the day you last ran the alert to the present) to ensure no documents are missed since the last time the Alert was run. To override the default date range, specify a date range in the query and run the search.


  • Notify you when there are new documents added to your area of interest

  • Let you set the mode and frequency of alert notifications, to suit your needs

  • Allow you to retrieve the query of the corresponding saved search to modify/refine your search

Creating an Alert

An "Alert" is a Saved Search which has notifications (alerts) set on it to ontify you of new results. So, an alert can be set from an existing search in "My Saved Searches". Or, you can create a new alert from the "My Alerts" page. 
To turn on an Alert from "My Saved Searches":

  1. Navigate to "My Saved Searches"

  2. Identify the saved search for which you need the alert, and select "Alert" from actions.

  3. Set the alert notification frequency and notification method.

Create a new alert from "My Alerts":

  1. Navigate to "My Alerts" page.

  2. Select "New", which is placed below the list of alerts (Even if you do not have any existing alerts, the "New" option is present in the "My Alerts" page).

  3. Enter a name for the new alert, and select "Create New".

  4. You are to the search page. You can perform your search, and use the "Save Alert" button to create your new alert. Your new alert is based on the newly saved query.

Note: When you create a new alert, you are first saving your search, and then setting alerts for that saved search. Which means whenever you create an alert, you are also creating a saved search with the same name.

Managing Alerts

"My Alerts" page lists the alerts set. An alert would have the same name as the saved search on which it is based.

If there are any new notifications for any of the listed alerts, it would be displayed separately, above the alert listing. You can select the link in the new notification to view list of new documents.

View the query for an alert

You can view the query on which the alert is based with the View option under Actions. When you select view, the search page would be displayed, with your saved query (search). If you wish, you can edit your query and save the modified query with a new name.

Change query of an alert

To change the query of an alert, you can use the Change Query option under Actions. But remember - an alert is based on a saved search. So when you change the query of an alert, you are changing the query of the corresponding saved search.

Change notification frequency/method 

You can change the notification frequency/method for an alert with Settings under Action.

Turn off an alert

To stop receiving notifications for an alert, you can use the Turn Off option. When you select an alert and turn it off, the alert would be removed from the alert list. The corresponding saved search would not be affected. So, if you ever wish to start receiving notifications, you can turn on the alert from "My Saved Searches".

Create an Account

FreePatentsOnline - Creating an account

FreePatentsOnline provides many value-added features to its account holders. You can create an account for free, and avail yourself of all the following:

  • Save your search queries for future use

  • Set alerts to notify you of new documents published in your area of interest

  • Save documents into multiple portfolios for reference and organization

  • Annotate your portfolios and saved documents

  • Share portfolios with your colleagues (and decide who has "read" versus "write" access)

Create an Account

Select the Create Free Account link in the top right corner of the home page. In the Account Sign up page, fill in the account sign up form.

The fields Name, Password, Retype Password, Occupation, Email and Confirm Email are mandatory, and are marked with a *. Checking the box to indicate that you have read the "Terms of Use" is also mandatory. You cannot leave a mandatory field blank or you will get an error upon submitting the form.

Your password

  1. Your password should be at least 6 characters long, and can have a maximum of 15 characters.

  2. Spaces, hyphens (-) and quotations (') are not allowed in passwords.

  3. Passwords are case sensitive.

Your email address

  1. Use an existing email address. The email address must be valid, as an activation email will be sent, and you are required to click on a link in the activation email before your account will function.

  2. Special characters like / (forward slash), " (double quotes), < (greater than symbol), > (less than symbol), ? (question mark), & (ampersand symbol) and \ (backward slash) cannot be used in the email address. These should not be found in email addresses anyway.

Activating your account

FreePatentsOnline has an email activation procedure. When you submit the sign-up form, you are then sent a verification email that contains an activation link. Once you click on this activation link, your account is activated.

The link in the activation mail will take you to FreePatentsOnline log in page. You can log in with the Email Address and password provided at the time of sign-up.

Logging in for the first time

The log in page will ask for your Email Address and Password. Email Address - Use the email address you had provided on the sign-up form. (Your activation mail shows your Email address under User Name). Password - Use the password you provided on the registration form.

Did not receive the activation mail?

Our system sends emails immediately. However, email takes a varying amount of time to be delivered on the internet, due to traffic conditions, your ISP, software settings, etc. We suggest giving the email at least 20 minutes to be received, but most of the time it should be much faster.

If you do not find the FreePatentsOnline activation mail in your inbox, check the SPAM folder too. It is possible that the SPAM filter of your mail account has mistaken our mail for SPAM.

SPAM filters are intended to keep out unsolicited email. Due to the volume of users we have, sends a lot of email. This occasionally causes email service providers to interpret our emails as SPAM.

To make sure you receive our email, you can whitelist emails from By whitelisting, you can set your email software to accept incoming email from a specific email address or domain, overriding your mail service provider's SPAM filter.

Logging In

The first time you accessed the FreePatentsOnline log in page, you did so by selecting the link in the activation mail. Once you have activated your account, and have logged in successfully, you can log in directly into FreePatentsOnline.

Type in the address box of your browser, hit return, and the FreePatentsOnline homepage will be displayed. To log in, select the link "Log in" at the right hand top of the home page.

The log in page

Once you have selected the Log in link, the log in page will be displayed. The log in page will ask for your email address and password. Use the email address and password you provided at the time of registration.

Successful Log in

Once you have successfully logged in, you will be taken to the FreePatentsOnline home page.

There are two things that would indicate your successful log in:

  1. There would be a personalized welcome message with your name, on the top right hand side of the home page.

  2. The main menu would have a second menu bar - the logged in menu, which lists the features available only to a logged in user.

Forgot your password?

If you have forgotten your password, we can assist you by resetting the password. If you have forgotten your password,

  1. Select Log in from the home page (top right hand side).

  2. Select the Forgot password? link below the log in button. 

  3. The Retrieve Password page will be displayed.

  4. Enter your email address, and press "Submit".

We will send you an email with a new password. Once you have received the mail, you can log in to FreePatentsOnline with your new password.

Remember: When copying the password from your email, ensure that no leading or trailing white spaces, punctuation or line breaks are copied.

Once you have logged in, you can Change your password, by going to My Account, and selecting the Change Password option in the right hand action box.

Remember me on this computer

You can save the trouble of re-entering your email address and password every time you log in by checking the "Remember me on this computer" option in the Log in page. This function sets a cookie that stores your user name. It will only work on that specific computer, and will only work if your browser is set to allow cookies. We do not suggest using this function on public computers.

What is a cookie?

A cookie is a small piece of data sent by our website to your computer, so that information related to the website can be remembered. No other site can read the cookie, and no sensitive information is stored anyway (only your username, not your password, is stored).

Remember: The "Remember me" feature would only work if cookies are enabled in your browser. Cookie enabling is different for different browsers, and you can find cookie-enabling instructions for all major browsers on the Internet.

Managing your Account

Once you have set up your account, you can view your account related information in the My Account page.

The My Account page displays all the information you had supplied at the time of registration. From the My Account page, you can:

  • Edit account information

  • Change your email address

  • Change your password

You can find these options at the bottom of My Account page.

Edit account information

To edit your personal information that you had given at the time of registration:

  1. Log in

  2. Select My Account from the main menu

  3. Select Edit Account Information (from the right hand action box)

Edit the required fields and select submit to update the changes you have made.

Remember: The fields - name, password, email address and occupation are mandatory. You cannot leave them blank.

Change Email Address

You can change your current email address from My Account page. To change your email address:

  1. Log in

  2. Select My Account from the main menu

  3. Select Change Email Address from the right hand action box.

The Change Email Address page asks for your current email address and new email address. Enter the email address you use to log in to FreePatentsOnline in the current email address box. Enter the new email address, and enter it once again in the respective boxes.

Note: FreePatentsOnline does not allow special characters like / (forward slash), " (double quotes), < (greater than symbol), > (less than symbol), ? (question mark), & (ampersand symbol) and \ (back slash) in the email address.

An email will be sent to you with an activation link to activate your new email address. You can activate your new email address by selecting the link in the activation email.

Remember: Your new email address will be effective only when you have activated it by selecting the link in the activation mail. Until that time, you can use your old email address to log in. Further, when you change your email address, your password will not change.

Again, if you do not find the FreePatentsOnline activation mail in your inbox, check the SPAM folder. It is possible that the SPAM filter of your mail account has mistaken our mail for SPAM. To make sure you receive our email, you can whitelist emails from

Change Password

You can also change your password from My Account page. To change your password:

  1. Log in

  2. Select My Account from the main menu

  3. Select Change Password from the right hand action box.

The Change Password page will ask for your current password, and your new password. Enter the password you use to log in to FreePatentsOnline in the box for current password. Enter your new password twice, to prevent typing mistakes.


  1. Your password should be at least 6 characters long, and can have a maximum of 15 characters.

  2. Spaces, hyphens (-) and quotations (‘) are not allowed in passwords. Periods (.) at the end of the passwords are also not allowed.

  3. Passwords are case sensitive.

Once you have entered the requested password details, you can select "Save" to change the password.


Portfolios are essentially an information management tool. Portfolios help you to effectively save and organize your information. In addition, you can view and share your information with others.

Portfolios actually complement saved searches. While saved searches allow you to save your queries and run them to view the results, portfolios help you to save your results list or save selected documents from the result list.

A portfolio helps you to:

  • Save the results or a set of selected documents from the results list for easy reference and further analysis.

  • Add comments in portfolios.

  • Add or remove any documents to any of the workfiles at any time.

  • Share selected portfolios with other account holders.

Portfolio Limits

In FreePatentsOnline, your account can have up to 5 portfolios, and 1000 documents total either across multiple portfolios, or in a single portfolio.

The maximum limit of 5 portfolios applies only to portfolios you have created. If you are the recipient of any shared portfolios, you can still have 1000 portfolios, apart from the shared ones.

Further while using Merge and Copy, the documents are being duplicated. So, while performing Merge and Copy, ensure that the maximum limit of 1000 is not exceeded (either in a single portfolio or across multiple portfolios).

Managing Portfolios

"My Portfolios" has two pages - the first page is the "My Portfolio" page, where all the portfolios are listed. The second page is the portfolio management page, where documents inside a specific portfolio are listed.

My Portfolios page

My Portfolios list all your existing portfolios, including the shared ones. A sharing icon besides the portfolio name indicates the shared portfolios. The portfolio list page provides the Name and Description of the portfolio and the date of last modification.

Managing your portfolios

In the portfolio list page, there are various options to manage the portfolios.

1. New portfolio: To create a new portfolio, select "New". Enter a new name for the portfolio to be created, and select New.

Note: The name can have a maximum of 25 characters.

Special characters like \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

2. Copy portfolio contents: You can copy the contents of a portfolio to a new portfolio with "Copy" option (except any portfolio shared with you on Read permission). Select the portfolio, the content of which you want to copy, enter a name for the new portfolio, and then select "Copy".

Note: The name can have a maximum of 25 characters.

Special characters like \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

Remember that while copying, the documents are being duplicated. So, while performing Copy, ensure that the maximum limit of 1000 documents is not exceeded (either in a single portfolio or across multiple portfolios).

3. Merge portfolios: You can combine the contents of two or more portfolios with the "Merge" option. You can merge the portfolios with "OR", or "AND" and "AND NOT".

Note: The content of the merged portfolios will remain intact, and the resultant documents after merging will be stored in a new portfolio. So, while performing Merge, ensure that the maximum limit of 1000 documents is not exceeded (either in a single portfolio or across multiple portfolios).

To merge two portfolios, select the portfolios you wish to merge and select the option with which you would like to combine them with. Give a name for the new portfolio to store the resultant documents in.

When naming the new portfolio, keep in mind that the name can have a maximum of 25 characters, and special characters like \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

You can use OR option to combine documents within the selected portfolios, avoiding duplicates.

E.g.: Portfolio A has documents 1, 2, 3 and 5. Portfolio B has documents 2, 3, 4 and 9. The resultant documents after merging portfolios A and B with OR would be 1, 4, 9 and 5.

You can use AND option to list the common documents within selected portfolios.

E.g.: Portfolio A has documents 1, 2, 3 and 4. Portfolio B has documents 2, 3, 4 and 9. The resultant documents after merging portfolios A and B with AND would be 2, 3, and 4.

The AND NOT option can be used to specify the portfolio, documents of which has to be completely avoided, while merging. AND NOT can be used in combination with either AND or OR

E.g.: Portfolio A has documents 1, 2, 3, 4 and 5. Portfolio B has documents 2,3, 4 and 9. Portfolio C has documents 2, 3 and 6.

Merging with OR and AND NOT - (Portfolio A OR B) AND NOT Portfolio C will have documents 1, 4, 5 and 9.

Merging with AND and AND NOT - (Portfolio A AND B) AND NOT Portfolio C will have document(s) 4.

4. Export the portfolio contents: The "Export" option can be used to export the contents of selected portfolios to an excel spreadsheet. You can export data from a maximum of 250 documents in selected portfolio(s) to an excel spreadsheet.

Data in the fields Document Number, Document Type, Publication Date, Title, Abstract, Inventor Name, Assignee, Application Number, Filing Date, and US Classes (only for US documents) will be exported into the excel sheet.

5. Delete portfolio(s): The "Delete" option can be used to delete selected portfolios.

Creating Portfolios

You can create new portfolios or add documents to portfolios from either the results list page or the patent details page. You can also create a new portfolio from "My Portfolios".

1. From the results list

Step 1. Perform a search in quick or expert search.

Step 2. From the search results listing page.

a. Add documents to an existing portfolio. All your existing portfolios are listed in the drop down.

Select the drop down option to view the existing portfolios. To select a portfolio, just click on it from the list.

b. Create a new portfolio and save your documents in it.

Enter a new name for the portfolio you are creating.

Note: The name can have a maximum of 25 characters. Special characters like \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

Once the selected documents have been added successfully, the Portfolio page will be displayed.

Options for adding documents

To add documents (to new or an existing portfolio), there are two options in the drop down menu - Checked or All.

You can use the first option (Checked) to save selected documents from the results list to your portfolio. The second option All, can be used to add the first 1000 documents in the results list to a new portfolio or an existing portfolio.

2. From the patent details page

Step 1. Perform a search, and from the results list for your search, select a document number. The details page for that document will be displayed.

Step 2. From the patent details page, add the document to

a. Add documents to an existing portfolio. All your existing portfolios are listed in the drop down.

Select the drop down option to view the existing portfolios. To select a portfolio, just click on it from the list.


b. Create a new portfolio and add the document to it. Enter a new name for the portfolio you are creating.

Note: The name can have a maximum of 25 characters. Special characters like \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

Once the document has been successfully added to the portfolio, you will be taken to the portfolio page.

3. Creating a new portfolio from "My Portfolios" page

Step 1. Select My Portfolio from the second line menu.

Step 2. Select "New".


Step 3. Enter a name for the new portfolio.

Note: The name can have a maximum of 25 characters. Special characters like \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

Once you have created the new portfolio, it will be listed in the My Portfolios page.

You can perform a search and add documents from the search result list page to the newly created portfolio. You can also add a document to the newly created portfolio from the patent details page. In both these cases, your newly created portfolio would be listed in the list of existing portfolios.

Manage Documents Inside a Portfolio

Portfolio Management Page

My Portfolios page lists all your existing portfolios, including the shared ones. You can select a portfolio name to view the Portfolio Management page, which lists documents within the selected portfolio.

By default, 50 documents are listed in a single page. You can use the "Show items/page" to change the number of documents listed in a page. The "Jump to" option can be used to jump to the Nth document listed. The previous/next and start/end navigation options can be used when there are documents listed in more than one page.

Edit name and description of a portfolio

You can edit the Name and Description of a portfolio with the "Description" option.

Note: The portfolio name can have a maximum of 25 characters, and special characters like \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

The portfolio description can have a maximum of 400 characters, and here also, special characters \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

Comment on a portfolio

You can add portfolio level comments with the "Comment" option in the Portfolio Management page.

Note: Special characters \ (back slash), ' (single quotes), " (double quotes), < (less than symbol), > (greater than symbol), ? (question mark), & (ampersand), / (forward slash) are not allowed.

When you share a portfolio, your comments are also shared with the recipient. And irrespective of the permission (read only or read/write) the recipient will be able to add comments.

Managing documents within the portfolio

The portfolio management page has various document management functions available like provision to:

  • Add documents

  • Copy and/or move documents across portfolios

  • Export document details to an excel spreadsheet

  • Add documents to shopping cart and

  • Delete selected documents

1. Add documents

As mentioned earlier, you can add documents to portfolios from the search results list page, the patent details page and/or the portfolio management page.

Use the Add option in the portfolio management page to add documents to the portfolio. To add documents, enter patent numbers one document per line. When a document number is entered without the country code/prefix, the entered number will be searched against the US collection.

US documents

Enter the document number with or without the prefix. E.g. US6000000 or 6000000, US20070144622 or 20070144622.

EP documents

Enter the document number with the prefix EP. E.g. EP1617750.

If you enter just an EP number with the prefix, all the available kind codes for that document are listed. If you enter EP0790279, documents



EP0790279B1 and

EP0790279B2 would be listed.

If you require a specific document, you can enter the number suffixed by the kind code. E.g. EP0790279B1.

WIPO/PCT documents

Enter the document number with the prefix WO. E.g. WO/2007/029035.

JP Abstracts

Enter the document number with the prefix JP. E.g. JP3867981

2. Copy documents

You can copy documents in a portfolio to one of your existing portfolios (except any portfolio shared with you on Read permission).

Select the documents to copy, select the portfolio to which the documents need to be copied and select Copy.

Remember that while copying, the documents are being duplicated. So, while performing Copy, ensure that the maximum limit of 1000 documents is not exceeded (either in a single portfolio or across multiple portfolios).

3. Move documents

Use Move to move selected documents within a portfolio to one of your existing portfolios (except any portfolio shared with you on Read permission).

Select documents to move, select the portfolio to which the documents need to be moved, and select Move.

4. Export the data from documents

You can export data from selected documents or a maximum of 250 documents to an excel spreadsheet.

Data in the fields Document Number, Document Type, Publication Date, Title, Abstract, Inventor Name, Assignee, Application Number, Filing Date, and US Classes (only for US documents) will be exported into the excel sheet.

5. Add to cart

From the portfolio details page, you can add documents to your shopping cart, and purchase the PDFs. You can either add selected documents to cart or opt to add a maximum of (first) 1000 documents.

6. Delete documents

To delete documents listed in a portfolio, select the documents and use the Delete option.

Share Portfolios

You can share a portfolio with one or more FreePatentsOnline subscribers.

From "My Portfolios" page, select the portfolio name you would like to share. From the Portfolio Management page, select "Sharing" option.

Sharing (either shared by you or shared with you) is a feature available to subscribers. Once you have canceled your subscription, all the sharing privileges would be withdrawn, and any shared portfolios will cease to be shared.

Provide the email address of the other FreePatentsOnline subscriber, with whom you would like to share your portfolio with, and select "Share". Once the portfolio has been successfully shared, message indicating sharing has been successful is displayed.

Select "Sharing" to view the sharing status for the portfolio. The list of people with whom the portfolio is shared will be displayed with the name of the recipient, and options to set permissions.

By default, when you share a portfolio, the permission is read only. Once you have shared a portfolio, you can provide the recipient either read or read/write permission, or even or stop sharing the portfolio with the recipient. You can do all these with options under "Sharing".

Read permission

Read permission gives the recipient permissions to copy and export the content of the shared portfolio, and add listed documents to cart.

The recipient will not be able to:

  • Edit the name and description of the portfolio

  • Add/Delete the content of the portfolio

  • Move the documents elsewhere, and

  • Share the portfolio with somebody else.

Read/Write permission

Read/Write permission gives the recipient same permissions as the owner of the portfolio.

Note: An individual user can have up to a maximum of 5 portfolios and save a maximum of 1000 documents across these portfolios.

This maximum limit is excluding any portfolios shared to you. I.e., if somebody else has shared one of their portfolios with you, you can still have 5 portfolios excluding the shared one.

Saved Searches

Saved Searches are meant to help you easily run frequently used searches. Saved searches save your quick and expert search queries so that they can be used afterwards - it saves you the trouble of remembering and re-entering the query. You can run a saved search at a later date to check for new additions to the search results. Saved searches also serve as the basis for setting alerts, to notify you when new documents of interest are published.

In a nutshell, with saved searches, you can

  • Save your complex search queries so that you can use them later

  • Run a search at a later date to check for additional search results

  • Retrieve the query of a saved search to modify/refine your search further, at a later time

  • Set alerts to notify you when new documents are added to your search result

Creating a Saved Search

Step 1. Perform a quick or expert search.

Step 2. In the search results page, enter a name for the saved search in the text box, and select "Save".

Step 3. "My Saved Searches" page would be displayed with the newly created saved search.

Managing Saved Searches

The saved searches page lists all of your saved searches. Once you have created a saved search, you can view the query you have saved, edit and save it if you wish. You can also set an alert for a saved search, to notify you when new documents matching your saved query are published.

Edit name and description of a saved search

You can edit the name and description of a saved search with the Edit option in Actions.

View the saved search

To view the saved search, select View, from Actions. When you select view, the search page would be displayed, with your saved query (search).

If you wish, you can edit your query and save the modified query with a new name.

Modify your saved search

You can modify your saved search with Change Query under Actions.

When you select change query, the search page would be displayed with your saved query (search). You can modify your search, and once you are done, you can save the modifications with the Save Search button.

Set Alerts

To set alerts use the Alert option under Actions. Set the alert notification frequency and method, and start receiving alert notifications whenever a new document matching your saved query is published.

Saved searches for which alerts have been set, would have an icon beside them. The icon indicates the alert notification method (email, in account or both email and in account).

Copy a saved search

You can copy a saved search and save it under a new name with the Copy option under the saved search listing.

Help on Patent Searching

Country Codes

This table has been compiled based on the latest codes supplied by the USPTO as well as codes applicable pre-2000. There are countries that have changed their names/country codes, post-2000. The pre-2000 codes would therefore aid search in such cases.

For example, Myanmar (MM) used to be Burma (BU). If you wish to search for patents relating to this country, you could select BU (pre-2000) and MM (post-2000)

Country Code     Pre-2000
Afghanistan AF  
African Intellectual Property Organization (OAPI) OA  
African Regional Industrial Property Organization (ARIPO) AP  
Ã…land Islands AX  
Albania AL  
Algeria DZ  
Andorra AD  
Angola AO  
Anguilla AI KN (Saint Christopher-Nevis-Anguilla)
Antarctica AQ  
Antigua and Barbuda AG AG (Antigua)
Arab States of the Gulf, Patent Office of the Cooperation Council for the (GCC Patent Office) GC  
Argentina AR  
Armenia AM  
Aruba AW  
Australia AU  
Austria AT  
Azerbaijan AZ  
Bahamas BS  
Bahrain BH  
Bangladesh BD  
Barbados BB  
Belarus BY  
Belgium BE  
Belize BZ  
Benelux Trademark Office (BBM) and Benelux Designs Office (BBDM) BX  
Benin BJ  
Bermuda BM  
Bhutan BT  
Bolivia BO  
Bosnia and Herzegovina BA  
Botswana BW  
Bouvet Island BV BV (Bouvetoya)
Brazil BR  
British Indian Ocean Territory IO  
Brunei Darussalam BN BN (Brunei)
Bulgaria BG  
Burkina Faso BF HV (Upper Volta)
Burma (see Myanmar)    
Burundi BI  
Cambodia KH  
Cameroon CM  
Canada CA  
Cape Verde CV CV (Republic of Cape Verde)
Cayman Islands KY  
Central African Republic CF CF (Central African Empire)
Chad TD  
Channel Islands (see Jersey or Guernsey)    
Chile CL  
China CN CN (China)
    CN1 (Tibet)
Christmas Island CX  
Cocos (Keeling) Islands CC  
Colombia CO  
Community Plant Variety Office (CPVO) QZ  
Comoros KM  
Congo CG  
Congo, Democratic Republic of the CD ZR (Zaire)
Cook Islands CK  
Costa Rica CR  
Côte d'Ivoire CI CI (Ivory Coast)
Croatia HR  
Cuba CU  
Cyprus CY  
Czechoslovakia (see "Czech Republic" and "Slovakia")    
Czech Republic CZ CS (Czechoslovakia)
Denmark DK  
Djibouti DJ AI (French Territory of the Afars and Issas)
Dominica DM  
Dominican Republic DO  
East Timor (see Timor-Leste)    
Ecuador EC  
Egypt EG  
El Salvador SV  
England (see United Kingdom)    
Equatorial Guinea GQ  
Eritrea ER  
Estonia EE  
Ethiopia ET  
Eurasian Patent Organization (EAPO) EA  
European Community Trademark Office [see Office for Harmonization in the Internal Market (OHIM)]    
European Patent Office (EPO) EP  
Falkland Islands (Malvinas) FK  
Faroe Islands FO  
Federated States of Micronesia FM  
Fiji FJ  
Finland FI  
France FR  
French Guiana GF  
French Polynesia PF  
French Southern Territories TF FQ (French Southern and Antarctic Lands)
French Territory of the Afars and Issas (see Djibouti)    
Gabon GA  
Gambia GM  
GCC Patent Office [see Arab States of the Gulf, Patent Office of the Cooperation Council for the]    
Georgia GE SU (Union of Soviet Socialist Republics)
Germany DE DD (German Democratic Republic)
    DE1 (Germany before 1942)
German Democratic Republic (see Germany)    
Ghana GH  
Gibraltar GI  
Gilbert Islands (see Kiribati)    
Great Britain (see United Kingdom)    
Greece GR  
Greenland GL  
Grenada GD  
Guadeloupe GP  
Guatemala GT  
Guernsey GG GB1 (Channel Island)
Guinea GN  
Guinea-Bissau GW  
Guyana GY  
Hague Agreement Concerning the International Deposit of Industrial Designs [per WIPO Standard ST.3, Page 3.3.5, Endnote 6] WO  
Haiti HT  
Heard Island and McDonald Islands HM  
Holy See (Vatican City State) VA  
Honduras HN  
Hong Kong Special Administrative Region of the People's Republic of China, The HK  
Hungary HU  
Iceland IS  
India IN  
Indonesia ID  
Iran, Islamic Republic of IR  
Iraq IQ  
Ireland IE  
Isle of Man IM GB4
Israel IL  
Italy IT  
Ivory Coast (see Côte d'Ivoire)    
Jamaica JM  
Japan JP  
Jersey JE GB1 (Channel Island)
Jordan JO  
Kazakhstan KZ  
Kenya KE  
Kiribati KI GE (Gilbert Islands)
Korea, Democratic People's Republic of KP  
Korea, Republic of KR  
Kuwait KW  
Kyrgyzstan (Kyrgyz Republic) KG  
Lao People's Democratic Republic LA  
Latvia LV  
Lebanon LB LN
Lesotho LS  
Liberia LR  
Libyan Arab Jamahiriya LY LY (Libya)
Liechtenstein LI  
Lithuania LT  
Luxembourg LU  
Macao MO MO (Macau)
Macedonia, The Former Yugoslav Republic of MK  
Madagascar MG  
Malawi MW  
Malaysia MY  
Maldives MV  
Mali ML  
Malta MT  
Marshall Islands MH  
Martinique MQ  
Mauritania MR  
Mauritius MU  
Mayotte YT  
Mexico MX  
Moldova, Republic of MD  
Monaco MC  
Mongolia MN  
Montenegro ME  
Montserrat MS  
Morocco MA  
Mozambique MZ  
Muscat (see Oman)    
Myanmar MM BU (Burma)
Namibia NA  
Nauru NR  
Nepal NP  
Netherlands NL  
Netherlands Antilles AN  
New Caledonia NC  
New Hebrides (see Vanuatu)    
New Zealand NZ  
Nicaragua NI  
Niger NE  
Nigeria NG  
Niue NU  
Norfolk Island NF  
Northern Ireland (see United Kingdom)    
Northern Mariana Islands MP  
Norway NO  
Office for Harmonization in the Internal Market (Trademarks and Designs) (OHIM) EM  
Oman OM OM (Oman)
    OM1 (Muscat)
Pakistan PK  
Palau PW  
Panama PA  
Papua New Guinea PG  
Paraguay PY  
Peru PE  
Philippines PH  
Pitcairn PN  
Poland PL  
Portugal PT  
Qatar QA  
Reunion RE  
Republic of Cape Verde (see Cape Verde)    
Romania RO  
Russian Federation RU  
Rwanda RW  
Saint Christopher-Nevis-Anguilla (see Anguilla)    
Saint Helena SH  
Saint Kitts and Nevis KN KN (Saint Christopher-Nevis-Anguilla)
Saint Lucia LC  
Saint Pierre and Miquelon PM  
Saint Vincent and the Grenadines VC VC (St. Vincent)
Samoa WS WS (Western Somoa)
San Marino SM  
Sao Tome and Principe ST  
Saudi Arabia SA  
Scotland (see United Kingdom)    
Senegal SN  
Serbia RS  
Serbia and Montenegro (Individual codes are available for "Serbia" and "Montenegro") YU  
Seychelles SC  
Sierra Leone SL  
Singapore SG  
Slovakia (Slovak Republic) SK CS (Czechoslovakia)
Slovenia SI  
Solomon Islands SB  
Somalia SO  
South Africa ZA  
Southern Rhodesia (see Zimbabwe)    
South Georgia and the South Sandwich Islands GS  
Spain ES  
Sri Lanka LK  
Sudan SD  
Suriname SR SR (Surinam)
Svalbard and Jan Mayen SJ  
Swaziland SZ  
Sweden SE  
Switzerland CH  
Syrian Arab Republic SY SY (Syria)
Taiwan TW  
Tajikistan TJ  
Tanzania, United Republic of TZ  
Thailand TH  
Tibet (see China)    
Timor-Leste TL TL (East Timor)
Togo TG  
Tokelau TK TK (Tokelau Islands)
Tonga TO  
Trinidad and Tobago TT  
Tunisia TN  
Turkey TR  
Turkmenistan TM  
Turks and Caicos Islands TC  
Tuvalu TV  
Uganda UG  
Ukraine UA  
Union of Soviet Socialist Republics (see Georgia)    
United Arab Emirates AE  
United Kingdom GB GB (United Kingdom)
    GB1 (Channel Island)
    GB2 (England)
    GB3 (Great Britain)
    GB4 (Isle of Man)
    GB5 (Northern Ireland)
    GB6 (Scotland)
    GB7 (Wales)
United States US  
Upper Volta (see Burkina Faso)    
Uruguay UY  
Uzbekistan UZ  
Vanuatu VU NH (New Hebrides)
Vatican City State (Holy See) VA  
Venezuela VE  
Viet Nam VN  
Virgin Islands (British) VG  
Wales (see United Kingdom)    
Wallis and Futuna Islands WF  
West Bank/Gaza PS  
Western Sahara EH  
Western Somoa (see Somoa)    
World Intellectual Property Organization (WIPO) [per WIPO Standard ST.3, Page 3.3.5, Endnote 6] WO  
Yemen YE YE (Yemen-San)
    YD (Yemen-Aden)
Yugoslavia [see Serbia and Montenegro]    
Zaire (see Congo, Democratic Republic of the)    
Zambia ZM  
Zimbabwe ZW RH (Southern Rhodesia)

Field Abbreviations

Note that most fields support Phrase (ABST/"cardboard box"), Proximity (ABST/"cardboard box"~5), Wildcard (ABST/card*), and Leading Wildcard (ABST/*ectomy) queries. Some fields support range queries and math operations. Only basic examples are provided below. See the syntax guide for advanced syntax details.

Field Abbr.

Field Name


Syntax Example and Comments


Assignee Address
(complete string)


AADR/"Route 66"




ABST/"titanium steel"


Assignee City


AC/"New York"




ACLM/"cardboard box"


Assignee Country






AGT/"Bacon & Thomas"


Agent Address City




Agent Country




Agent Name ?




Assignee Name ?




Filing Date

Date ?

Single Date: APD/1/5/2012
Range: APD/1/1/1790->12/31/2001


Application Number




Assignee State




Assistant Examiner Name ?




US Class




Document Number
(same as PN)

Number ?



ECLA Classification




Field of Search




Foreign Patent Reference
(entire string)




Foreign Patent Reference
(number only)

Number ?



Inventor Address
(entire string)


IADR/"main street"


Inventor City




Inventor Country




Inventor Name ?




IPC Classification




IPC Revised




Inventor State (U.S.)




Publication Date

Date ?

Single Date: ISD/1/5/2012
Range: ISD/1/1/1790->12/31/2001


Kind Code




Other References




Parent Case


PARN/"application Ser. No. 704,848"


Primary Class




Publication Date

Date ?



Primary Examiner Name ?




Patent Number
(same as DN)

Number ?



Priority Country




Priority Number

Number ?



Foreign Priority




Document Type



Possible values:
U (Utility)
RE (Reissue)
D (Design)
PP (Plant Patent)


US Patent Reference
(entire string)




US Patent Reference
(number only)

Number ?



(a.k.a. Description)








Additional fields are available via our API for commercial use. Please inquire if you would like access to these, and other, fields: Assignee Count, Claim Count, Expiration Date (with term extensions), Family Member Count, Image Count, Inventor Count, Priorities Count, Reference Count, Word Count, Assignment Count.

Field Descriptions


A summary of the patent, useful to quickly determine the general idea of the invention.


An attorney (US) or representative (EP) authorized to act for, or in place of the applicant and who is registered to practice before the Patent Office.

Agent Address City (AGTC)

Field Name Syntax Example and Comments
Agent Address City AGTC/Paris


Agent Country (AGTCN)

Field Name Syntax Example and Comments
Agent Country AGTCN/JP


Agent Name (AGTN)

Field Name Syntax Example and Comments
Agent Name AGTN/smith


Application Date

The date on which a patent was applied for.

Application Number

The number assigned by the Patent Office when a patent application is submitted. It is not the number that is assigned to a patent itself. In the US, the application number is a 2-digit series number followed by a slash and then a 6-digit serial number. (Example: 10/007521). For EP patents the application number is an 11-digit number where the first 4 digits indicate the filing year of the application. (Example: EP20010402190).

Application Type

A single-digit number, which indicates the type of patent, filed with the US Patent Office.

1 = Utility (U)

2 = Reissue (RE)

4 = Design (D)

5 = Defensive Publication (T)

6 = Plant (PP)

7 = Statutory Invention Registration (H)


The person or entity to whom the inventor assigns the patent rights. If a patent document shows no assignee, this means the ownership of the patent was retained by the inventor. Ownership rights can also be assigned after a patent is issued. If this is the case, the assignee may not be present in the patent document but will be recorded in the Patent Office prosecution history file.

Assignee Address (AADR)

Field Name Syntax Example and Comments

Assignee Address

Field Name Syntax Example and Comments
Assignee Address
(complete string)
AADR/"Route 66"


Assignee City

The city of the patent assignee. This field is mostly applicable for US patent documents.

Assignee Country

The country of the patent assignee.

Assignee State

The state or territory in which the patent assignee is located.

Assistant Examiner

The person who examines a patent application under the supervision of a primary examiner.


A formally worded statement within a patent application or patent, which clearly explains the invention; the claims define the scope of the invention.


Also called Specification of a patent, this is a part of a patent where the inventor describes, illustrates and discloses the invention in detail. The description of an invention must describe in detail the invention so that someone who is skilled in the same art can reconstruct the invention from the description and drawings alone. Failure to do so can mean refusal of the patent by the Patent Office.

Designated States

List of Member States specified by the inventor/applicant when filing an application with WIPO or EPO.

Document Number

The patent number or published application number. It is prefixed with a two digit country code (US, EP) followed by the patent number or published application number.

  • Document Range
  • US Patents
  • US Applications
  • US Design
  • US Plant
  • US Reissue
  • European Patents
  • PCT Patents
  • Japanese Abstracts

Document Type (PT)

Field Name Syntax Example and Comments
Document Type PT/PP

Possible values:
U (Utility)
RE (Reissue)
D (Design)
PP (Plant Patent)


Domestic Reference

This field contains earlier patents and publications filed in the same country as the subject patent and disclosing inventions similar to the one claimed. They are prior art references cited by the Patent Office during patent examination.


Illustrations that are used to describe the patent. They show the invention from a variety of views so that all details are viewable.


The classification scheme assigned by the European Patent office to patent documents in order to facilitate prior art searches. ECLA is constantly being revised and updated.

Field of Search

X100 grade steel pipes

Filing Date

See Application Date.

Foreign Patent Reference (FREFN)

Field Name Syntax Example and Comments
Foreign Patent Reference
(number only)


Foreign Priority Data

A field that contains data indicating in which foreign country a US application claims priority.

Foreign References

A field that contains the list of foreign patents and foreign applications cited as references by the subject patent.


Acronym for "International Patent Classification". This is the organizational system used by the European Patent Office (EPO).


Revised International Patent Classification or IPC8. The IPC-8th edition has two classification levels. The Core Level and the Advanced Level. The advanced level is revised every three months whereas the core level is updated every three years. The advanced level is generally used by large patent office whereas the core level is used by small and medium patent office.


One who contributes to the concept of an invention.

Inventor Address (IADR)

Field Name Syntax Example and Comments
Inventor Address IADR/"main street"


Inventor City

The city in which inventor of the patent resides. This field is mostly applicable for US patent documents.

Inventor Country

The country in which inventor of the patent resides.

Inventor State

The state in which inventor of the patent resides.

Kind Code

A code which includes a letter and in many cases a number, used to distinguish the kind of patent document (example, publication of an application for a patent) and the level of publication (example first publication, second publication or corrected publication).

Locarno Classification

The Locarno Classification is a classification for industrial designs. This classification is based on a multilateral treaty administered by WIPO, called the Locarno Agreement. The Locarno Classification consists of 32 classes and 223 subclasses with explanatory notes and an alphabetical list of goods in which industrial designs are incorporated.

Other References

This field contains prior art reference in the form of books, journals, articles, abstracts and other non-patent documents that are cited by the Patent Examiner during patent examination.

PCT 102(e) Date

If a US patent or international application was filed on or after November 29, 2000 and if its corresponding WIPO publication is in English and designates the US, the 102(e) date is the international filing date or an earlier filing date for which a benefit is properly sought.

PCT Filing Date

The date on which a US international application was filed with WIPO.

PCT Number

A number assigned to a US international application when it is filed with WIPO under the Patent Cooperation Treaty (PCT). Example: PCT/JP98/04875

PCT Publication Date

The date on which a US international application filed under the Patent Cooperation Treaty, was published by WIPO.

PCT Publication Number

A US international application published by WIPO. Example: WO99/25029

Parent Case Text

A field that contains data describing prior applications (continuations, continuation-in-part, division, provisional application etc) related to the subject patent.

Primary Class (PCCL)

Field Name Syntax Example and Comments
Primary Class PCCL/702/100


Priority Country

The country in which the earliest filing of a patent application is claimed.

Priority Date

The date which, for patent law purposes, is assumed to be the date of invention. This is often the same as the application date, but often may be up to one year earlier due to foreign patent applications which may serve as proof of date of invention.

Priority Number

A patent application number in respect of which priority is claim. Multiple priority numbers can be present in a patent document.

Publication Date

The date which a patent is granted. This is often several years after the Application or Priority Date.

Reference Cited

A list of prior art references cited by the Patent Office during patent examination. This includes earlier patent and publications disclosing inventions similar to the one claimed.

Referenced By

A list of patents that cited the subject patent.


Title of the patent.

US Classification

A system used by the USPTO using a 3-digit class and a 3-digit sub class. There are about 450 classes of invention and about 150,000 subclasses of invention in the USPC. A single invention can have more than one classification code. In such case, the first classification is listed as primary class and any other listings are placed under other classes.

US Patent Reference (REFN)

Field Name Syntax Example and Comments
US Patent Reference REFN/6000000

Patent Searching - Overview

What data does this site have?

We have hundreds of gigabytes of full-text data which is keyword searchable using the most powerful search engine in the industry. In addition to our full-text data, we have terabytes (a terabyte is 1000 gigabytes) of images so that you can view patent diagrams. The specific full-text data that you can search is:

  • US Patents*: 3930271 to 9209844
    (PDF/Image available from 0000001 onwards)
  • US Reissue Patents*: RE28671 to RE45816
    (PDF/Image available from RE00001 onwards)
  • US Design Patents*: D242583 to D744717
    (PDF/Image available from D000001 onwards)
  • US Plant Patents*: PP3987 to PP26194
    (PDF/Image available from PP0001 onwards)
  • US Statutory Invention Registration (SIR): H000001 to H002293
    (PDF/Image available from H000001 onwards)

*Full-text is not available for some documents prior to 1976, and for a small number of documents after 1976, due to incomplete data entry by the USPTO. Note that our US collection is more comprehensive than the USPTO's due to the incorporation of other data sources for US documents and our own OCR efforts

What is a patent search?

A very broad description might be that a patent search is the process by which prior inventions or ideas are examined, with the goal being to find information that bears close similarity to a given patent or proposed invention.

If that description is not very enlightening, don't worry - it is necessarily vague because there are many different kinds of patent searches, and it is hard to capture the essence of each type in a single description. Detailed descriptions of each type of search will be presented later.

The documents searched during a patent search may include U.S. and foreign patents, published patent applications, and non-patent literature, such as the Web, product literature, and scientific journals and databases.

Who needs a patent search?

There are many possible reasons for needing a patent search. Some examples are:

  • an inventor would like to make sure his invention is unique before he spends time and money to obtain a patent (this would be a Novelty search).
  • a company would like to produce a product, and although they do not wish to patent the product themselves, they want to make sure that they do not get sued by someone else that might have already patented the idea (this would be an Infringement search).
  • Company A is making a product, and is being sued by Company B, which believes it holds a patent on the product, and Company A would like to prove that Company B's patent is invalid (this would be a Validity search).
  • a researcher would like a comprehensive listing of the most recent patents in a certain field, to help guide his research (this would be a State-of-the-Art search).

Search Tutorial

Conducting a Patent Search

1. A note on syntax

One point that we must emphasize is that you must make sure you are familiar with the search language for the database you are using. Unfortunately, none of the different search engines use the exact same search language. If you assume that you can use the same syntax from one patent searching site to another, you are going to have a problem. Often, that problem will be obvious because a syntax error will be reported when you try to run the query. However, you may not get an error! Your query might run just fine, but since the syntax is different, the query will not mean what you intended it to mean. You will get results for a different query than you intended (which almost certainly means you will miss relevant references), and if you don't realize what you did, you may never even know. Learn the syntax of the site you use!

2. Boolean Logic

Boolean logic (named after the mathematician George Boole) refers to logical relationships between sets. For our purposes, those sets are the sets of results from a search engine.

For instance, a search for "bicycle" might return one set of references, while a search for "wheel" would return a different set of references (some of which probably overlap with the "bicycle" references). But, what if we want a set of results that encompasses the references for both of those terms? We use Boolean commands to tell the search engine to combine the two sets.

The commands used in Boolean logic include "and", "or", and "not" (the USPTO web site uses "ANDNOT" in place of NOT, but we will use NOT here for the purposes of clarity - just realize that you will need to use ANDNOT when actually searching at the USPTO web site). In the example above, if we wanted to all references that contained "bicycle" or "wheel", the search would simply be: bicycle OR wheel.

It would be incorrect to construct the search as: bicycle AND wheel. Why? Use of the "AND" command would only return references that contained both the word "bicycle" and the word "wheel". That is very different than returning all results that contain "bicycle" OR "wheel".

And this query: bicycle NOT wheel, would mean yet something else. It would mean the set of all references to bicycle, with any overlapping references from the set of "wheel" results removed.

We assume that most people are familiar with Boolean operators, and their use in search engines. However, the reason the topic bears discussion is that, while the examples above are quite simple, extremely complex searches can be constructed using Boolean operators. The use of the operators, along with the use of parentheses, if necessary, must be done carefully to make sure that you are constructing the search that you think you are constructing. Here is a more complex example:

bicycle AND wheel NOT (spokes OR seat)

What does that mean? It means the set of all references which contain both bicycle and wheel, but which do not contain either spokes or seat. Note the use of parentheses to indicate grouping. If the query was written without the parentheses, it would mean something different:

bicycle AND wheel NOT spokes OR seat

Without the parenthesis you have requested all references which contain bicycle and wheel, but not spokes, or references which contain seat but not spokes. The first query returns a few thousand results, while the second query returns a few HUNDRED THOUSAND results! So, they are quite different.

The moral of the story: Be careful when constructing your searches. They will get even more complicated when you start adding in date terms, class and subclass terms, and all sorts of other variables. Make sure you asked the search engine what you intended to ask it, and always examine your search results critically so that if any logical errors have occurred, you will detect them.

While technically perhaps not a part of Boolean logic, wildcard characters are important enough, and universal enough, that we will discuss them here. A wildcard character is a special character which means "any character or characters". Wildcards are very helpful in increasing the flexibility of your search queries. Let's examine a hypothetical example:

You are doing a search for a new kind of steel and one of the important points is that it is extremely light compared to other similar materials of the same strength. You have decided that you must use "light" in your keywords, but you realize that there are many forms of the word "light", including "light", "lighter", "lightest", and perhaps "lightweight". You want to be sure that you find any possible form of the word. Since you just learned about the Boolean operator "or", you know you could write such a search like so:

light OR lighter OR lightest OR lightweight

But, that becomes very cumbersome. And what if you forgot one??? Wildcards make this easy. You can write it like so:


The wildcard character says to the search engine "Find me anything that starts with 'light', followed by any other characters (or no other characters)."

A lot simpler, right? The only drawback is that it can be less specific that using all those "or" commands. When you write it all out with "or", you know exactly what it is looking for. When you use wildcards, there might be words that match that you did not think about and are not relevant to your search. In this case, any patents containing "lighting" would be found also. So would any patents containing "lighthouse", or worse yet "lights" - there are probably thousands of patents containing the word "lights". So, maybe this particular use of wildcards isn't a good idea.

That does not mean you should not use wildcards. It just means you need to be careful. If your use of wildcards causes you to accidentally include some common word that is not relevant to your search, you could waste a lot of time. But, if used wisely, they can ease the construction of your queries and make them more comprehensive.

Word stemming can often substitute for wildcards, and will be discussed later.

3. Keyword Searching

Keyword searching is the heart of a good patent search (although class/subclass "hand" searches have their place also). You can use Boolean logic, date ranges, class and subclass designations, and a variety of other commands to construct just about any search you can imagine.

Assuming that you are familiar with Boolean logic, and the search syntax (a summary of our syntax is available elsewhere), the next thing to do is decide on keywords. Determining the best keywords to use requires some thought, and is very important to getting good search results.

Always remember this: The inventors may not have used the words that come first to your mind. Think of every possible way to describe the invention. Think of words that any patent on the topic absolutely MUST contain, and then words that the patents PROBABLY contain - but they might not. It is crucial to develop a good list, and then implement the searches with appropriate logic. For instance, assume that we are searching for an invention having to do with bicycle tires. The word "bicycle" is almost certainly in any relevant patent. Is the word "tire" in any relevant patent? Probably - but maybe not. Maybe the inventor uses the word "wheel" instead. Or maybe even "rim" (although they are not really the same - do not assume that everyone uses words perfectly accurately).

So, the search that you would want to use might look like this:

bicycle AND (rim OR wheel OR tire)

Understand? If this is not clear to you let us know - we will give you a crash course in search logic and you will be all set.

Once you construct your search, see how many results you get. You will always have a limited amount of time that has been authorized for a search. Most likely it will be 6-12 hours on a patentability search. Given this fact, YOU CANNOT LOOK THROUGH MANY THOUSANDS OF TITLES. There simply is not time. So, if you perform a search and it returns over a couple thousand results, you probably need to rethink your keywords and target your search a bit more carefully. In the above example, the search "bicycle AND (rim OR wheel OR tire)" returned 3000 results, what would you do? I would modify the search like this:

bicycle AND tire

and then see how many results that came back with. Tire is the most important keyword after bicycle. If that cuts it down to somewhere under 1500, then you have an amount that you can probably get through in a reasonable amount of time. If you have more time after you finish reviewing the results of that query, you might try:

bicycle AND wheel ANDNOT tire

Why the "ANDNOT tire"? Because that prevents you from getting any of the same results you got the first time around - it would be a huge waste of time to look through redundant results.

Note: This was a simple example. Often, there will 10 or 20 keywords that you might want to use, and instead of constructing a single search that returns a thousand results, you will use multiple searches, each with different sets of keywords, that each return a few hundred results or less.

4. Advanced Keyword Syntax and Techniques

a. Quotes

b. Word Stemming

Word stemming is a language related tool, which determines the root of a word first, and then retrieves all possible variants.

When you search with word stemming ON, documents in your results list would have both the root word, and the variants of the root word. With word stemming OFF, your search is limited to the exact word.

For both quick search and expert search, word stemming is turned ON by default.

Search term

Word stemming

Matching results would have the word(s)


On (searches for variants of compose)

Compose, composes, composed, composing, composable, composition etc


Off (searches for exact word)



On (searches for variants of the root word "compose")

Composition, Compositions, Compose, composes, composed, composing, composable etc


Off (searches for exact word)



On (searches for variants of the root word "metal")

Metallic, Metal, Metals etc.

c. Search Term Weighting

Some of your search terms would be more important than others. Search term weighting helps you to tell the search engine which term is more important, and how important it is over the other term.

FreePatentsOnline uses the "^" (caret) operator to facilitate search term weighting. Combine this with relevancy sorting option to display the most accurate results at the top of the list.

The caret - "^" should be followed by a whole number that indicates the relative importance increase. For example, "^2" means that the word is twice as important as a word with no caret, while "^3" means three times as important, etc.

Note: Ensure that there is no space left between the keyword and the weighting operator.



DNA^5 or RNA

DNA is 5 times more important to the relevancy of documents than RNA. Finds all documents with either DNA or RNA, or both, but all other factors remaining the same, rank documents with DNA higher.

d. Wildcards

Truncation or Wildcard searching allows you to retrieve documents containing variations of a search term. Wildcard symbols can be used to replace a single letter or a part of a word, or one or more numbers.

FreePatentsOnline use two wildcards: ? to replace exactly one character or number. * to replace zero or multiple characters or numbers.


Results list would have


Analyse and Analyze


Sulphur and Sulfur


Harbor and harbour

5. Class/subclass searching

You can find the relevant classes/subclasses, and enter them into the Advanced Search (the search syntax for that would be "ccl/xxx/xxx"). This will return all patents in a given class/subclass. You then scan every title, and read documents of interest in more detail. This is often called a "hand search".

To search an entire class, use a wildcard for the subclass (ccl/xxx/*). This would allow you to see all patents under a particular class, but would be impractical for a class that contains a large number of patents.

This seems a lot simpler than keyword searching, right? You do not have to try and guess what words are in relevant patents. You do not have to try and figure out many alternative ways of describing the same device. But, there is a catch. Just like you can never be sure what words an inventor used, you can never be certain in what class/subclass a relevant patent will be found. Often there are multiple possibilities because of classes overlapping, and sometimes you may even find outright mistakes, where a patent is filed in a class in which is just should not be. A good keyword search will find a relevant patent, no matter which class or subclass it is in. You will NEVER find an erroneously classified patent via a class search.

Alas, some people like class/subclass searches (and they do have their place, when trying to be as thorough as possible, to augment keywords searches, but they are not a substitute for keyword searching). This is probably a result of old habits dying hard: a few years ago there was no such thing as keyword search and so hand searches were the norm.

How do you know what the most relevant classes are? The most common way to figure this out is to do a keyword search first, and use the classes/subclasses listed on documents found during that search. You can also keyword search the class/subclass definitions, or ask an examiner (covered previously).

6. Date Range Searching

Let's pretend we want to do a Validity search on patent, 1,234,567, filed on August 7, 1994, that claims "a lighter, more aerodynamic design for a bicycle rim by using an oval cross-sectional shape". We have decided that the keywords we want to search on initially are "bicycle" and "rim". What is the syntax for the search we want to construct? Remember, nothing filed after August 7, 1994 counts, because we have to prove the present inventor WAS NOT THE FIRST to invent such a thing, so all relevant prior art must pre-date his application. The search is thus:

APD/1/21/1790->8/17/1994 AND bicycle AND rim

That means, "All patents applied for between January 21, 1790, and August 17, 1994, that contain the words bicycle and rim". Why 1790? That is the first year that the U.S. patent office existed. You can use 1790 always, just to be safe, or, in a high-tech field, you can use a more recent year if you are sure it pre-dates the development of the technology. "APD" is the abbreviation for Application Date here and at the USPTO. Again, know the syntax of the search engine you are using!

7. Assessing Search Results

Now that you have constructed your search, you find that there are hundreds or thousands of results. How do you know what is useful and what to ignore? To answer that question, we need a bit of background on patent law (DO NOT CONSTRUE THIS, OR ANYTHING ELSE ON THIS SITE, AS LEGAL ADVICE. SEEK APPROPRIATE COUNSEL).

The Test for Obviousness

When a patent examiner reviews an invention, the most difficult task he is faced with is deciding if the invention is "unobvious". As an aid to addressing this issue, the following theoretical question is posed: "Given an inventor with average skill in the appropriate arts, average creativity, and a complete knowledge of the prior art, would he have come up with this invention?" If the answer is yes, then the invention may be judged an obvious extension of existing technology, and therefore not patentable.

Note that the use of the phrase "a complete knowledge of the prior art" means just that - complete. The hypothetical inventor is assumed to have knowledge of each and every piece of prior art known to man that is relevant to the invention under examination.

So, the criterion for "unobviousness" is not simply knowing facts that someone else did not know. It is more a question of inspiration; of exceeding the average level of creativity possessed by the hypothetical inventor.

Isn't this quite a subjective criterion? Absolutely, but that is how it is done. The objective is to prohibit people from obtaining patents on trivial modifications of existing inventions. For instance, if you had invented a new kind of bicycle, would it be fair for someone else to be granted a patent for a bicycle that was identical to yours, except that they had chosen to specify that it was made of a different material, or perhaps had a frame whose angles differed by tiny amounts (and they had no data to prove that these tiny changes improved the functioning of the bicycle in any substantial way)?

No, that would not be fair. And they would never get a patent due to such trivial changes, because their "invention" would be judged an obvious extension of yours.

The Doctrine of Equivalents

The concept of the Doctrine of Equivalents goes hand-in-hand with the test for obviousness. The Doctrine of Equivalents is a mechanism which broadens the scope of claims to include subject matter that is not explicitly claimed, but which would be considered equivalent by an expert in the field.

For instance, let's go back to our hypothetical bicycle patent. We had stated our claims as:

Claim 1: A lighter, more aerodynamic design for a bicycle rim by using an oval cross-section.
Claim 2: The rim of Claim 1 where the cross-sectional piece is formed from aluminum.

Suppose those were our only two claims. Now suppose that a competing bicycle manufacturer made a rim almost identical to ours, but they made the rim out of another high-strength, lightweight allow, such as titanium, or magnesium.

We sue them, alleging that such a trivial modification should not permitted. Our argument is that it should be obvious to anyone familiar with bicycle rims and the materials out of which they are made, that making the same rim, but out of a different alloy, is still an infringement of our patent. They have done nothing novel. In fact, the different alloy they used is even well-known to those in the bicycle industry, so the modification required no creativity at all.

Their counter-argument is this: "You had an opportunity to state in your claims exactly what your patent was to legally cover. If you had desired to do so, you could have included magnesium and titanium along with aluminum in your Claim 2. Or, you could have rephrased your Claim 2 to state that the rim was formed from aluminum or any other high-strength, lightweight alloy. You didn't. You should not be allowed to claim that our modification infringes on your patent when it was your own lack of forethought or bad writing that caused you to omit the proper language which would have made it clear that you intended to claim more materials than just aluminum".

Who is right? There is no clear-cut answer to that question. Both sides have legitimate points. In fact, this murky issue is so important that the Supreme Court has addressed it at least twice in recent history, once in 1997 and once in 2002, both times affirming the use of the Doctrine of Equivalents. Of course, like the test for obviousness, just what is "equivalent" and what is not, is a judgment call that must be made on a case-by-case basis.

The main difference between the test for obviousness and the Doctrine of Equivalents is in when they come into play. The test for obviousness comes up during the process of examining a new patent application. The Doctrine of Equivalents is not used for patent applications. Rather, it is applied to the claims of an existing patent by the court system when deciding whether someone is infringing.

So what does all this have to do with patent searching? Quite a bit. The point behind all this is simply this: When conducting a search, you do not need to find prior art that EXACTLY mimics the invention in the disclosure. If you find the exact invention in the prior art, it is said that the prior art "anticipates" the invention. Anticipation is great when it happens, but most of the time you are going to find prior art that is close, but not an exact match. And that's fine - because of the obviousness test, and the Doctrine of Equivalents, extremely similar prior art may serve just as well as anticipation.

Enough Background! What is relevant and what is not???

Now that you understand how patent examiners and judges determine whether one invention is unallowably close to another invention, how do you, the patent searcher, decide what prior art to cite when conducting a patent search?

Just like the application of the obviousness test or the Doctrine of Equivalents is a judgment call, so is what prior art to cite. However, you have a much easier time of it than a patent examiner or a judge. Why? Because rather than trying to be fair, you are trying to be thorough. When an examiner or a judge is in doubt, they still have to come to a decision, no matter how tough it is. You do not, because you follow this simple rule: If in doubt, cite it. It is much worse to leave out a relevant reference than it is to waste a bit of time by citing a reference that may later be determined to not be relevant.

i. Inventions with Few Features

Note that most disclosures only have a few points on which you will be searching. For instance, the disclosure might describe a bicycle, but the search would not be on an entire bicycle, but rather on a specific piece of a bicycle which was novel, such as an improved rim or an improved pedal. The disclosure should make it clear what aspects of the device are the subject of the search.

In the normal case of a disclosure with no more than a handful of important points on which to search, anything that parallels an important feature in the disclosure is relevant. The prior art that you cite does not need to parallel every aspect of the invention; it may share only one important feature. So, if you believe that you have found prior art that anticipates an aspect of the disclosure, or if you believe that a judge or examiner would consider it an obvious modification of the disclosure, cite it.

Note that it is better to find a single piece of prior art that addresses all facets of the disclosure, but that is not always possible, so you cite several patents that, together, build up a case for each point in the disclosure being anticipated or obvious.

ii. Inventions with Many Features

You may want to search on an invention that has numerous important aspects. This can occur with a complex invention with many supposedly-novel aspects, or in patents that seek to patent a multi-step process.

So what happens where the invention is a 10-step process, and not all of these steps are necessarily novel (though some may be), but the combination of these particular steps in that particular order is novel? Do you cite every piece of prior art that mentions any of the steps in any context? Probably not - it's a judgment call.

iii.Where Can Prior Art Come From?

The simple answer is: anywhere! For instance, when searching patents for prior art, it does not matter if you find relevant information in the Background, in the Abstract, in the Summary of the Invention, in the Detailed Description, in the Figures, or in the Claims. If relevant information is present, you can use it.

From the standpoint of efficiency, you will usually have a pretty good idea if anything worthwhile is going to be found in a given patent by reading the Abstract, and then the Summary of the Invention. If those sections look promising, but you haven't found exactly what you are looking for, use your browser to search for specific words in the patent - often the quote you want is buried in the Detailed Description and there is no point in reading a 50 page patent to find that one gem when you can use the "find" function on your web browser.

Similarly, when looking for prior art in non-patent literature, the information can come from anywhere (subject to the date requirements of certain types of searches). A web site is fine. A technical journal is fine. A book is fine. Even product literature or promotional material is fine. Anything that serves to document, in reasonable detail, that the concepts you are searching for already exist (or already existed before a given date when dealing with Validity searches) should be cited.

How are patents organized?

There are many patent offices around the world, and their patent classification systems are not the same. Luckily, most of the systems are based on very similar principles. And, knowledge of the United States Patent Office (USPTO) system and the European system is all that is required for the vast majority of patent searches.

1. The USPTO patent classification system

a. Understanding the "Dot" System
The United States Patent & Trademark Office (USPTO) classifies patents by subject matter. There are hundreds of different categories, and each of the categories has many sub-categories (and often, each of the sub-categories has sub-categories). A partial listing of one class might look like this:
1A - With process control system
4.6 - .Traveling wave type
4.7 - ..Electron beam device
4.8 - .Gyromagnetic type (e.g., ferrite)
4.9 - .Semiconductor type (e.g., with semiconductor diode)

In this example, the class is 330. 330 is all about "Amplifiers". Each entry under 330 is a sub-category listing specific features of amplifiers. The location of a patent is written as its class, followed by a slash, and then its subclass, like so: 330/4.

What would you expect to find in a patent that was classified as 330/4? You would expect to find an amplifier (because everything under class 330 must be an amplifier), using a maser-type amplifying device (since that is the definition of subclass 4). It makes no difference if you know what a maser-type amplifying device is; this is just an example.

Now, what if you had an amplifier with a maser-type amplifying device that also had a process control system (the definition listed for subclass 1A)? How would you know where to look for related inventions? Would you look in 330/4, or would you look in 330/1A?

The answer is "both". There is no way of knowing under which class/subclass the USPTO examiners decided to file an invention. And, a single invention can be filed under more than one class/subclass (in fact, most inventions are filed in several classes/subclasses).

This is one of the most important challenges of patent searching: Thoroughly understanding the classification system, and wisely choosing which classes/subclasses appear to be most relevant to the search you are performing. If you choose poorly, there may be another class/subclass filled with dozens of patents relevant to your search, and you may miss them.

Don't worry too much though - there are ways of making sure that you are looking in the correct classes/subclasses, and we will explain how to do this in a bit.

You may have noticed the dots in front of the definitions for subclasses 1A, and 4.6 - 4.9. What are they? The dots indicate additional hierarchy levels in the class/subclass structure. In this example, the class (330) is at the highest level; everything else falls under class 330. But only some of the subclasses are directly under class 330. For instance, subclass 1R is directly under class 330. So are subclasses 2, 3, 4, 4.5, and 5. You know this because they have no dots in front of their definitions which would indicate additional steps down in the hierarchy structure. Subclass 1A on the other hand, is not directly under class 330. Rather, subclass 1A actually falls under subclass 1R. So, you could think of subclass 1A as being sub-subclass 1A.

Now look at subclass 4.7. It has two dots in front of its definition. That means it is still further down the classification tree. 4.7 is under 4.6, which is under 4.5, which is under class 330. So 4.7 is actually a sub-sub-subclass. But, all those "subs" would get to be confusing, so they just call them subclasses and distinguish the different levels with dots - the more dots, the lower it is in the hierarchy. If you are trying to figure out what class or subclass a given category falls under, go up the listing from the category of interest to the first class or subclass with one less dot.

It works just like an outline, but dots are used in place of Roman numerals, and other traditional outline level designations.

It is extremely important to understand this hierarchical system. If you do not understand the classification system, it is absolutely impossible to know if you are looking in right places when you do a search.

Here is an actual screen-shot of another partial class listing, with annotations:

b. Subclasses are Not Cumulative
Be aware that upper level subclasses do not contain all the patents of the subclasses below them. In the example above, subclass 2 is indented under subclass 1. This does not mean that, if you did a search of subclass 1, you would find all the patents in subclass 2, plus some additional ones that were specific to subclass 1. It does not work that way. You must search the subclass at the lowest relevant level of the hierarchy. Patents are only filed in the upper levels of the hierarchy when there is no appropriate lower level in which to file them. To illustrate this concept, here is a very simple imaginary example:

Class 999 Cars
1 - .with blue paint
2 - ..with metallic paint
3 - .with red paint
4 - .with black paint

Where would you look for a car with blue metallic paint? Only 999/2. Because there is a specific subclass for blue metallic paint, all patents should be filed in that subclass. Filing mistakes aside, if you look in 999/1, you will find nothing - that is not the proper place, even though it is also for blue paint.

Where would you look for a car with green paint? In the main class, 999. This is because there is no subclass with an appropriate definition, leaving the examiner with no option other than to file the patent in the top level. So, only patents that do not have a more concise subclass available are filed in a given place. Or, to say this another way, patents are filed in the most detailed subclass available - so that is where you must look for them. Higher level classes and subclasses are only for patents which cannot be filed in a lower level subclass.

c. Class and Subclass Definitions
A class and subclass searching and definitions are coming soon!

One tidbit of information to keep in mind for US classes/subclasses is that letters after a subclass (such as the "1A" and "1R" in the Amplifier example above) are special designations used for USPTO internal purposes. Because they are not official classes, they are ignored for definition purposes. In other words, 330/1R is often treated as if it were just 330/1. This distinction is of little importance, but it can be confusing if you do not know that sometimes the end letter is simply ignored.

2. Foreign Patent Classification Systems

There are two other classification systems in common use in Europe. These systems are called the "IPC" (International Patent Classification) and the "ECLA" (European Classification).

The format of these classifications is as follows. A sample IPC would be C12N 7/00; it consists of a section (letter-C), class (numbers-12), subclass (letter-N), main group (numbers-7), a slash, and the subgroup (numbers-00). However, it may be as short as a section and class.

ECLA is really an extended version of the IPC system. ECLA adds addition letters or numbers on to the end of the IPC classification on to the end to allow for more categories, and thus hopefully more accurate categorization.

While the categories themselves are different from those found at the USPTO, the concept of searching the IPC or ECLA classifications is the same. Note that many US patents will have their foreign classifications listed on them as well, and this can be a helpful guide when trying to determine what foreign classes to search.

A guide to the IPC can be found at and the IPC can be searched via keyword here: Note that ECLA codes cannot currently be searched by keyword. However, the ECLA codes are so similar to the IPC codes that this is largely unnecessary.

3. Help with Patent Classification

One method of making sure that you know which classes are relevant to a particular invention is simple (at least when it comes to US Patents): Ask! USPTO examiners are very willing to help you. The USPTO examiners are experts at classifying the inventions in their particular area, so it is good to get their opinion on where to search even if you think you have already located the best classes.

USPTO examiners have a duty of confidentiality. So, you can tell them whatever you want about the invention and they are not allowed to tell anyone else. Also, this is part of their job, so don't feel like you are imposing (but be VERY POLITE!). Many search firms contact examiners as a matter of course to get their opinions on what classes should be searched -- so the examiners expect it.

How do you go about doing this? First, you need to figure out what you think the most relevant class/subclass is. A good way to know this is to look at the classifications of the patents that you found in a keyword search, if you did the keyword search first. Or, take a few minutes to find some patents related to something similar to the disclosure invention, and see where they are classified. Once you have that information, there is a web page where you can look up what "Art Unit" handles a given Class or Subclass. An "Art Unit" is just a group of examiners that work on related subject matter.

So, let's say that you determine that the most relevant class/subclass for your search is 359/009 (Lasers and Holograms). You would go to this web page:
and enter "359" in the class blank. Press the button, and you get a table that lists all of the Art Units that work on class 359. Scan down the subclass column, and you will see that Art Unit 2872 handles subclass 9. With that information in hand, you then visit this web page:

In the "Search by Organization" blank, enter 2872. That gives you a list, with phone numbers, of all the examiners that work in Art Unit 2872. So, you just pick one, give them a call, and say "Hi, I'm working on a novelty search about an invention which has these features... I think that I should be searching Class 359 Subclass 9, but I just wanted to make sure. What do you think?"

Sometimes they will say "Yes, you are correct". Sometimes they will give you some additional places to search. And sometimes they will say "I think you have the wrong Class/Subclass. You might want to try 283/86 (Printed matter with holograms), but my Art Unit doesn't work on that Class/Subclass, so try giving them a call".

This is really a detailed explanation for a simple step - just bookmark those web pages and it should only take 10 minutes or so.

Note that occasionally the USPTO's database is unavailable and the Art Unit search will not work. If that happens, you may find appropriate phone numbers on this page as well:

4. Understanding Patent Numbers

When searching patents, you will encounter a variety of different patent numbering formats. For instance, you may see the same U.S. patent referred to as "6,000,000" or "US06000000" or even "US6000000B1."

Each of these designations means the same thing, but different databases present the numbers differently. The "B1" on the end of the last example simply stands for "granted patent", which brings us to the topic of Kind Codes.

There are many different designations, called Kind Codes, which can be appended to patent numbers and patent application numbers. Each Kind Code has a specific meaning, and while often not relevant for the purposes of patent searching, you should understand that Kind Codes exist so that you are not confused by them. Following is a table listing all current U.S. Kind Codes. Some of the table comments address the fact that the use of Kind Codes has not been consistent throughout history, so older patents may use different designations than current patents.

Note that foreign Kind Codes look similar, but they do not always have the same meanings. So, DO NOT assume that "A1" in the US means the same thing as "A1" elsewhere.

Kind Code

Kind of Document



Published Patent Application

Pre-grant publications begin to be published in March 2001. Format for publication number includes the year of publication followed by 7 digits. Example: US20030005000 A1


Republication of Patent Application



Corrected Publication of Patent Application




Patent having no previously published pre-grant publication. Example:US6000000 B1. Patents published before January 2001 retain the Kind code A.



Patent having previous pre-grant publication; new B2s begin to be published after March 2001.

C1, C2, C3

Reexamination Certificate

Reexam Certificates published prior to 2001 retain the codes B1, B2, etc.


Reissue Patent

Example: USRE12345E.


Statutory Invention Registration (SIR)

Example: USH1234H.


Published Plant Patent Application

Pre-grant publications begin to be published in March 2001


Plant Patent

Patent having no previously published pre-grant publication. Example: USPP12345P2. Plant patents published before January 2001 retain the Kind code P.


Plant Patent

Patent having previous pre-grant publication; P3s begin to be published after March 2001


Republication of Plant Patent Application



Corrected Plant Patent Publication



Design Patent

Example: D123456S

In addition, you will come across US patents with completely different numbering formats, including things such as D123456 (the "D" indicates that it is a design patent), PP01234 ("PP" indicates a plant patent), and RE12345 ("RE" stands for reissue).

It behooves you to have a basic understanding of these different numbering schemes. As patent searches rarely involve design patents or plant patents, reissues will be the most relevant to your searching (though even they will be rare). A reissue occurs when something in a previously-granted patent is found to be in error, and the patent must therefore be amended.

Finally, a document that you will rarely encounter, but should know that it exists, is the Statutory Invention Registration (SIR). The SIR is a document that allows an inventor to put an invention into the public domain. The SIR is not a patent, and does not afford any patent rights to the inventor. What it does do, however, is prevent anyone else from patenting the invention. SIR's replaced a previous type of document called a "Defensive Publication". Defensive publications no longer exist, but may be recognized by their unique numbering scheme, which starts with a "T", as in T998008.

Patent numbers are assigned sequentially by issue date (but SIRs are numbered sequentially by application date).

Following is a table the lists the first number for each type of patent issued in a given year. This information can help you perform "common sense" checks on your search results. For instance, if you are doing a Validity search, and your references must pre-date another patent with a priority date of Jan 1, 1990, and you see that you have included a reference to US patent, you know something might be amiss, because that patent was issued (not applied for) in 2001. Technically, you could be correct. The Priority Date on the patent could be before 1990 in certain circumstances, but it is unlikely.

Issue Year

1st Utility

1st Design

1st Plant

1st Reissue

1st Statutory Invention Registration






Did not exist






Did not exist

























































































































Know What You are Looking For

Before we talk about the specifics of different patent searches, we need to define a very important patent searching concept: the "disclosure". The disclosure refers to the document which explains the invention or concept on which you are going to search. Depending on the search type, and your role in the patent search process, the disclosure may take different forms.

If you are an inventor conducting your own search, you might not have a disclosure at all. You might just have an idea in your mind as to what you are looking for. If you are a professional patent searcher, you will likely have a disclosure from your client or employer. If you are an inventor and have not written a disclosure, we suggest you do, even if just to get your own thoughts in order - it will help you search more effectively.

The disclosure for Novelty searches and Infringement searches describes the proposed inventions or products. The disclosure may be anything from informal document with rudimentary sketches of the invention to a complete patent application with professional drawings, or even an existing patent.

Based on the disclosure, you should be able to answer this question: What are the novel points of this invention? The reason for this is that you are going to be searching for prior art relevant to the aspects of the invention that are novel - which is not necessarily the entire invention.

For instance, given a disclosure about a bicycle with non-slip pedals, the points of novelty might be the particular shape of the pedals, or the materials that the pedals are made of, or some type of locking mechanism that keeps your feet from coming off. Of course, the disclosure may talk about bicycles in general, and the diagrams may include pictures of entire bicycles, not just pedals. That does not mean that any patent about bicycles is relevant. You must understand which features are common knowledge and simply present to put the invention in context versus which features are potentially patentable.

In a State-of-the-Art Search, the objective is often to find out what other people in the field are doing. A State-of-the-Art search may not be based on a specific invention at all, but rather the disclosure may simply be something like "Find all patents that discuss the use of magnesium alloys in bicycle frames".

The disclosure for a Validity search will normally be an existing patent. You will be given a patent number, and you will need to look the patent up, read it, and thoroughly understand the patent - particularly the Claims.

While disclosures may take different forms depending on the exact situation, it is always imperative that you know what you are looking for. It will save time, help make your search results concise, and help ensure that you do not miss anything relevant.

Patent Search Types and Methodologies

There are many different types of patent searches, including Novelty searches (also called Patentability searches), Infringement searches (also called Clearance, Freedom to Operate, or Right To Use searches), Validity searches (also called Invalidity, or Enforcement Readiness searches), and State of the Art searches (also called Collection searches). Each type of search has a different purpose, and demands a different search strategy.

1. Novelty Searches

The Novelty search, also referred to as a Patentability search, is the most common type of patent search. Novelty searches are conducted when an inventor has an invention which he is interested in patenting, and wishes to determine if anyone has previously invented anything similar or identical.

Novelty searches generally have no date constraints on the prior art. In other words, if you find prior art that reads on the invention, it does not matter whether the prior art is from yesterday or 100 years ago - it is relevant. The reason for this lack of date constraints has to do with patent law: Anything that has already been disclosed to the public, in any manner, at any time, cannot be patented.

2. Validity Searches

The idea behind a validity search is that the Patent Office may have issued the patent (or allowed specific claims contained in the patent) in error. Examiners are pretty good at what they do, but they are not infallible and they are often operating under severe time constraints. They may have missed a relevant piece of prior art, and this resulted in them granting a patent with claims that never should have been allowed.

The situation with a Validity search is often that a company has made a product that infringes upon another company's patent, and they are being sued as a result. One way to win an Infringement case is to invalidate the patent in question. If a patent search can locate prior art that reads on the claims of the patent in question, those claims will be struck from the patent. The patent owner then loses his legal right to sue over products that would infringe on those claims.

Whereas a written description of the invention forms the basis of a novelty search, validity searches are done on existing patents, and that patent will serve as the disclosure.

Note that with a Validity search, the idea is to find prior art that is relevant to the validity of the CLAIMS of the subject patent. Read that again: the CLAIMS. Not the general idea. Not the entire patent, but each claim, one by one. As a result, this is normally a more time-consuming search than a novelty search.

A successful Validity search finds references that the Patent Office missed (you might think this is rare - but it is not), and thereby provides evidence that the claims should have been disallowed on the grounds that someone had already come up with the invention before the patent in question was filed.

Pay close attention to the word "filed". The application filing date is very important in Validity searches because it determines the priority date (sometimes called a "get behind" date, for reasons that should become apparent) of the patent. It doesn't matter when a patent issued - it matters when it was filed. You must prove, for each claim, that inventions were known which were so similar to the claim in question, before the filing date of the present patent, that the claims should not have been allowed.

Or, in layman's terms, you are attempting to prove that the inventor of the patent in question was actually NOT the first person to come up with this invention. Only the first inventor can hold a valid patent.

Let's use a fictional example to illustrate what we mean:

U.S. Patent 9,999,999, in Claim 1, claims a computer chip that is faster and generates less heat than any other chip on the market. The patent was filed for on 1/1/2002, and granted on 2/1/2003.

In searching the prior art, you find two pieces of prior art that contain information which is very similar to claim 1 of the subject patent. Piece "A" is an article from a computer magazine, dated 11/01/2001. Piece "B" is a patent which was filed for on 4/1/2002 and issued on 12/1/2002.

Which of these references is relevant? The answer is "A". Piece "A" came before the filing date of the patent in question. Although Piece "B" issued before the patent in question, it was not filed before the patent in question. Only the filing date matters, because that documents who conceived the invention first, not who got it through the approval process the fastest.

Note: In general, when conducting a Validity search you do not cite any prior art that has already been cited on the front of the subject patent. This prior art in listed on the patent because it has already been reviewed by USPTO examiners and, since the patent was granted, the examiners obviously felt that those references were not similar enough to the invention at hand to stop the patent from issuing. In some cases the examiners may have been wrong, but proving that is an uphill battle as compared to finding prior art of which the examiners were unaware.

Note that while it is the CLAIMS of the subject patent with which we are concerned (in other words, we are searching on the claims), the art cited may come from anywhere (just like in a Novelty search). Relevant art does not have to be from the claims of other patents.

Let's now revisit the idea of dependent and independent claims. Remember our fictional example where Claim 1 read "A lighter, more aerodynamic design for a bicycle rim by using an oval cross-sectional shape", and Claim 2 read "The rim of Claim 1 where the cross-sectional piece is formed from aluminum?".

If you were doing a validity search and you had to prioritize finding prior art to invalidate one of these claims, which would you choose?

Well, if you find prior art that invalidates Claim 1, then there is no oval rim to be made of aluminum! Claim 2, being dependent on Claim 1, is destroyed by destroying Claim 1. For this, and other reasons, independent claims are normally the targets in a Validity search - it is more efficient to try and invalidate independent claims because you automatically get the dependent ones in the process. You will know a claim is independent if it has no reference to another claim in it.

Also called "Right-to-Use Searches", "Clearance Searches", or "Freedom-to-Operate Searches", the point of this type of search is to prove that a proposed product or invention does not violate any active patents (or conversely, to at least be aware that it does, and make the appropriate business decision).

Keep these things in mind for an Infringement search:

  1. You are normally only searching patents. Non-patent literature is normally not necessary, since the issue is whether or not the client would infringe an in-force patent.
  2. You must carefully read the Claims of each patent you find that might be relevant. Remember, it is the Claims, not the descriptions found elsewhere in a patent, which determine what it would take to infringe that patent.
  3. Only in-force patents are of concern, so make sure you limit your date range to the last 20 years.

As we have already stated, Infringement searches are generally conducted by trying to prove that no in-force patents exist with claims that would cause the client a problem.

But, what if you are confident that such an invention or patent already does exist, but it is over 20 years old? A viable alternate in some very specific cases might be to try and prove that the invention is in the public domain, and therefore safe to use. This would be done by showing that the invention had at one time been disclosed, but that the disclosure occurred over 20 years ago.

4. State-of-the-art searches

The term "State-of-the-Art Search" often means different things to different people. Therefore, if you are a professional patent searcher it is crucial to understand what the client is asking for before beginning this type of search (as it is with any search, but perhaps more so here). Generally, a State-of-the-Art Search is designed to quickly allow someone to see what is currently being developed in a given field. During such a search, the searcher picks patents representative of a specific technology, but does not cite every patent having to do with the technology, as there would be a great deal of redundancy. However, sometimes a client may want each and every patent on a given technology. This type of search is more properly called a Collection Search, but the terms are often used interchangeably.

Quick Search

Quick search lists the most common search fields. You can search for a word or a simple phrase or patent number in any of the listed fields. You can search in more than one field at a time. You can also use wildcards to enhance your searches in quick search (see wildcards for tips and examples for searching with wildcards). Boolean operators and nesting are not allowed in quick search. Quick search also has additional features like word stemming, sort order and date range to further enhance your search. In both quick search and expert search, the collection searched is defaulted to US patents. To change the collection searched, just select the required collection from the collection options provided.

Expert Search

Expert search helps you create complex queries to search multiple fields using field abbreviations. You can also include boolean operators, nesting and wildcards in your expert search query. To add value to your searches, FreePatentsOnline incorporates proximity searching and search term weighting features in expert search. Word stemming, sort order and date range options are available to further enhance your search. In both quick search and expert search, the collection searched is defaulted to US patents. To change the collection searched, just select the required collection from the collection options provided.

Sort Order

You can select to sort the documents in your results list either chronologically or according to their relevancy. If you select chronological sort order, documents in the results list would be arranged chronologically, with most recently published documents on the top of the list. You can also select to sort the documents in the results list according to their relevancy. Relevancy sorting is based on a "relevancy score" assigned to each document. Relevancy score is based on frequency and positioning of keyword(s) in the document. Relevancy score ranges from 0 to 1000. Documents with higher relevancy score would be placed at the top of the list.

Boolean Operators

Boolean operators help you combine words or phrases to broaden or narrow your search. You can use boolean operators to specify what you want and what you do not want while searching. FreePatentsOnline allow AND, OR and NOT operators.

Boolean Operator




Mobile and Telephone

Finds documents which have both mobile and telephone.


Mobile or Telephone

Finds documents which have either mobile or telephone or both.


Mobile not Telephone

Finds documents which have only mobile. The NOT operator excludes telephone completely.

Order of precedence for boolean operators is:

  1. NOT
  2. AND
  3. OR

Which means that in a query with NOT, AND and OR, terms connected by NOT would be processed first, followed by terms connected by AND and lastly, those connected with OR. Example: auto or manual and gear - Since AND is processed before OR, the query would be interpreted as auto or (manual and gear). Note: FreePatentsOnline search engine is not case sensitive for boolean operators.

Nested Queries/Creating queries with Parentheses or Brackets

You can enclose search terms and their operators in parentheses or brackets to specify the order in which they should be processed. Information within parentheses is read first and then information outside parentheses. If there are more than one set of parentheses, the innermost set of parentheses would be read first, then the next and so on until the whole query is interpreted. The order of precedence for parenthesis and boolean operators is:

  1. Parentheses
  2. NOT
  3. AND
  4. OR

Nested query

How it is interpreted (following order of precedence)

Hair and dye or colorant

(Hair and dye) or colorant

(one or two and layer) and insulation

(one or (two and layer)) and insulation

Proximity Searching

Proximity searching helps you to specify how near/distant you want your search terms to be. You can specify the distance or nearness of the terms searched as whole numbers. The proximity operator in FreePatentsOnline is "~". The proximity operator should be followed by a whole number indicating the proximity of the search terms. For example, "~10" means within ten words of each other. Note: Ensure that your keywords are enclosed in inverted commas, and there is no space left between the inverted commas and the proximity operator.


Results list would have

"Enzyme peptide"~3

Documents with both enzyme and peptide, where both are within 3 words of each other.

"fermentation bacteria milk"~5

Documents where the words fermentation, bacteria and milk, are present within 5 words of each other.

Start here if you already know to search at the USPTO

The search language used by is extremely similar to that of the USPTO. This is no accident. The search at the USPTO is fairly robust (although subject to some limitations, which we will discuss momentarily). It allows keyword searching across a large number of fields, date range searching, and it allows the combining of multiple search criteria with complex Boolean logic. In addition, the use of a similar syntax to the USPTO's search makes the learning curve to use our search engine trivial for the many IP professionals already familiar with the USPTO syntax. For users already familiar with the USPTO's search syntax, we briefly describe the added features of our search.

Differences from the USPTO:

In general, we have designed our search language so that a search that works at the USPTO will work on our search engine (this may not be true for some of the more rarely-used fields at the USPTO -- a complete list of the fields we support can be found below, and on the search page). However, while a search constructed using the USPTO's language will generally work on our search engine, if you limit yourself to using just the USPTO syntax you will be missing out on a great deal of the power of our search engine. Luckily, learning to use all the extra power of the FreePatentsOnline search engine only requires knowing about two extra commands, plus a button on the advanced form.

The Button: Word Stemming

Usage example: With word stemming on, 'metal' will also locate other forms of the word, including 'metals', 'metalized', and 'metallic'. Word stemming is a method of determining the root of a word, and then all possible variants. This is accomplished with a sophisticated formula called the Porter Stemming Algorithm. When it comes to the technical terms often required to express patent concepts, no dictionary even comes close to containing all the words that would be needed. So, rather than rely on an incomplete dictionary, the Porter Stemming Algorithm uses the rules of English (our apologies to those searching non-English documents, this function only works for English at this time) to find words that contain common roots. Now you don't have to miss documents because you were looking for a "metal widget" while the inventor chose to call it a "metallic widget." (Yes, you could use Boolean logic to construct the query "metal OR metals OR metallic OR metalized" but do you really want to do that every time? And are you sure you thought of all the forms of the word? Really sure?). Note that the effect of word stemming on the number of results is fairly significant. The statistics will vary from word to word, but for instance, a search on the word "metal" with word stemming on returns about 16% more results than with word stemming off. You certainly do not want to miss 16% of the potentially relevant documents in your prior art searches! Word stemming is set to "on" by default, and can be turned off by clicking the appropriate button under the search box.

The '~' Command: Proximity Searching

Usage example: "aluminum widgets"~10. Proximity searching is a way to find words that are near each other, rather than a literal phrase in which the words must be right next to each other. Unfortunately for patent searchers, it's easy to say the same thing many different ways -- even when using the same key words. What if you want to find patents about aluminum widgets? You would rather not search for 'aluminum AND widget', because with both "aluminum" and "widget" being very common words (ok, widget probably isn't really that common, but you get the point), that search could return far too many patents to look through in a reasonable amount of time. You could search for the phrase "aluminum widget?" (with the '?' allowing for widget OR widgets), but that is going to miss a ton of patents. What if the inventor said "widgets made of aluminum", or "aluminum may be used to make said widgets", or "the widgets may be made from any of the group comprised of aluminum, bronze, steel, titanium or copper"? You wouldn't find any of those by searching for a literal phrase. That's where proximity searching comes to the rescue. The query "aluminum widget"~10 would find every one of those, while at the same time excluding documents where aluminum and widget were so far apart that they probably had nothing to do with each other. '~' finds words that are in proximity to each other, and you can control how close the two words must be to count as a successful match. The number that follows the '~' indicates how many words are allowed to be between the two keywords. We suggest that 10 is a good distance to start with, but you may find that other values work better for your needs.

The '^2' Command: Search Term Weighting

Usage example: cat^2 OR dog. You may know that some of the search terms you are using are more important than others. If that is the case, the '^' command lets you increase the relative weight of a particular word. Then, the relevancy ranking formula uses this information to return the most accurate results at the top of the list. The caret "^" should be followed by a whole number that indicates the relative importance increase. For example, "^2" means that the word is twice as important as a word with no caret, while "^3" means three times as important, etc.

The '*' and '?' Command: Wildcard Searching

Usage example: electron*, su?. Wildcards are used to match patterns. The single character wildcard '?' represents a single character query. (e.g. su? will search for words like sub, sun, sum etc). The string wildcard '*' represent multiple character queries. (e.g. medic* will search for words like medic, medicine, medicant, medicinal, medicate, etc). The USPTO uses '$' for wildcard searching instead of '*'. However '$' should be the last character in the word. allows you to position the wildcards anywhere inside a word, except at the beginning. You can also combine '*' and '?' (e.g. dep?n* would search for words like depend, dependent, dependence, depending etc). Wildcard searches that create too many word matches may sometimes result in a "search-too-broad" error. It is therefore advisable to be more specific when using wildcards. (e.g. elec* would search for words like elect, elects, electron, electrons, electric, electrical, electricity etc. If you are only interested in patents dealing with electronic, use "electron*" to eliminate the other words. Note: Word stemming should be OFF when using wildcard searches.

Summary of Differences from USPTO Syntax:

Once you understand word stemming, proximity searching, search term weighting and wildcard searching you have mastered the main differences between the USPTO and our site. These search abilities are deceptively simple -- don't underestimate their power to find just what you want to find.

Start here if you already know how to search at Delphion

The main difference between Delphion and this site is that we follow the USPTO's convention of specifying a field name by putting it in front of the word, followed by a slash, like so: IN/smith. That means find the word "smith" in the Inventor's Name (IN) field. The equivalent command when using Delphion would be "smith IN". That's really the only change you need to make, except of course be sure to use our field name abbreviations. Also, make sure you understand our syntax for proximity searching and search term weighting.

Syntax Examples

Basic Field Abbreviations and Boolean Operators

Query Description


Find all documents containing the word 'cat' in any field.


Find all documents containing the word 'cat' in only the abstract. (‘ABST’ can be replaced with the abbreviation for any text field)

cat AND dog

Find all documents containing both the word 'cat' and the word 'dog'. The two words may be in different fields.

ABST/cat AND dog

Find all documents containing the word 'cat' in the abstract, and the word 'dog' in any field.

TTL/cat NOT dog

Find all documents containing the word 'cat' in the title, but do not include any documents which have the word 'dog' in any field.

(cat OR dog) AND (leash OR fence)

Find all documents that contain either the word 'cat' or the word 'dog', and which also contain either the word 'leash' or the word 'fence.' Note that without the parenthesis this query would be interpreted in an entirely different manner due to binding order of AND versus OR. Parenthesis are very helpful in making sure your query mean what you intend.

Dates, Date Ranges, and Date Math




Find documents with only this specific application date. (‘APD’ can be replaced with any date field)


Find all documents with an application date between the first date and the second date, inclusive.


‘NOW’ is a convenient way to specify “today” in dates. Note that in Alerts and Saved Searches, ‘NOW’ automatically takes on the meaning the current day.




Dates may be added or subtracted. Legal values include DAY, MONTH, YEAR, NOW and literal dates. Excellent for automatically updating date windows in Saved Searches and Alerts, and for finding in-force patents without typing the date each time (e.g., to always find patents applied for no more than 20 years ago, use APD/NOW-20YEAR->NOW).

Advanced Functions



[with word stemming on] electroplate

Find all forms of the word 'electroplate', including 'electroplated', 'electroplating', and 'electroplater'. Word stemming is based on language rules and may not find all forms of all words (to be more inclusive, use wildcards).

“cat dog”

Phrase query. Find the phrase “cat dog” with no intervening words, in that order. Wildcards are not allowed (e.g., “cat do*”).

"cat dog"~5

Proximity query. Find all documents containing the word 'cat' within 5 words of 'dog'. The 5 may be replaced with any whole number.

cat^5 OR dog

Search term weighting. ‘Cat’ is 5 times more important to the relevancy of matching documents than ‘dog’. Find all documents containing the word 'cat' or 'dog' but, all other things being equal, rank the documents containing cat higher. The "5" may be replaced with any whole number.


Unlimited Character Wildcard. Find documents containing words starting with ‘cat’ like cats, cathode, category, etc. Useful when you need to be more inclusive than word stemming allows.


Single-character Wildcard. Find all documents containing words that has only one character after 'do' like doe, dog, dot, etc.

US State Codes













































































































Information for Inventors

Invention Promotion Companies

Invention Promotion Companies: Caveat Emptor!

Many invention promotion companies provide little or no value to the inventor. They prey on the inventor's desire to bring his product to market, making false promises about their ability to promote the product, sometimes supported by their own "market studies" of dubious value. Unethical companies are such a problem in this area of business that the FTC has a page on this topic to warn inventors: In addition, the USPTO has published a Scam Prevention warning on this topic.

Do not deal with any invention promotion company that you have not thoroughly checked out through the FTC, Better Business Bureau, and other appropriate agencies.

Inventor Contact Details

Do you have inventor contact details?

Regarding inventor contact details, inventor details listed in our patent details page are the only details we can provide. To know more about an invention or a product based on an invention, you can try contacting the assignee (who would usually be the employer of the inventor) listed in the patent details page.

USPTO Fee Schedule

USPTO Fee Schedule, Pendency Info

The USPTO fee schedule is described in the USPTO site. Link to this section is given below:

Patent Term Glossary

Patent Term Glossary


To relinquish the rights to an invention.

Agent Type

Applicants of international applications may be represented by Attorneys or Agents registered to practice before the USPTO or by an applicant appointed as a Common Representative. If the applicants have not appointed an attorney or agent or one of the applicants to represent them, and there is more than one applicant, the applicant first named in the request and who is entitled to file in the USPTO shall be considered to be the common representative of all the applicants.


The communication from the applicant to a Patent Office requesting that a change is made to the patent application after it is filed.


Annual payment to keep patent or patent application alive in some countries. In the US, similar fees are due 3.5, 7.5 and 11.5 years after issue. This is also called "Maintenance Fees".


An invention is said to be "anticipated" when virtually the exact same idea, without even having to argue obviousness of trivial modifications, is found in the prior art.


The person who files a patent application. In the US the applicant is always the Inventor. In other countries, the applicant and assignee are the same.

Application Publication

A pre-grant publication of a patent application at 18 months from priority date.

Art Unit

A group of patent examiners assigned to handling a specific type area of technology.

Article of manufacture

A simple object made by humans or machines. Articles of manufacture include all devices, and are one class of inventions covered by patents.

Assignee Type

A 2-digit number code used by the US Patent Office to define the type of assignee.
01 - Unassigned
02 - United States company or corporation
03 - Foreign company or corporation
04 - United States individual
05 - Foreign individual
06 - U.S. Federal government
07 - Foreign government08 U.S. county government
09 - U.S. state government


Transfer of ownership rights from the inventor to someone else.


The patent owner who transfers ownership of the patent to another entity (assignee).

Base Claim

The first member of a patent family, which may or may not be the first member published.

Basic Patent

The best manner of practicing the invention or the best operative example known to the inventor.

Certificate of Correction

Certificate issued upon patentee request, due to a minor error in the patent such as printing, typographical or clerical errors.


A reference to a document considered relevant to the examination of a patent application. Citations may be made by the or by the applicant.


A category, organized by subject matter, into which patents are classified. Classes are the highest level of organization and there are several hundred of them.

Clearance Search

See Infringement Search.


An inventor whose name appears with at least one other inventor in a patent application and who has contributed to the patent invention. Also called Joint Inventor.

Collection Search

A patent search conducted for the purpose of providing a general review of a given area of technology. May be referred to as a State-of-the-Art Search.


Chemically significant substances (such as a formulation for a drug, or a fuel). Compositions are one type of invention covered by patents.


Patent searchers must keep all information provided by clients confidential. To breach this trust opens a searcher up to lawsuits, not to mention dismissal.

Confirmation Number

A four-digit number, which the US Patent Office assigns when an application is filed, and uses to make sure that any papers filed later on, are assigned to the right file.


An application based on an earlier filed patent application, wherein there are no new disclosures, but may contain new claims. The most common situation where this occurs is when an applicant is having difficulty in proceeding with the original claims because the examiner keeps rejecting them.


An application (also called CIP) that is filed when a new improvement is conceived after filing of the original application. The CIP thus contains the original filed invention and the newly claimed invention. Material in common with the earlier application has the original application's filing date and new material has the filing date of the CIP.

Control Number

A unique number assigned by the USPTO when a patent reexamination request is filed. This is a two-digit series code (example: 90 for ex parte reexamination requests; 95 for inter partes reexamination request), and a 6-digit control number.


Legal right granted to exclude others from selling, performing, copying, or displaying a work of authorship (music, writing, etc.)

Date of invention

Can be the date a patent application was filed, or the date the author can prove the invention was invented or even conceived, providing he then showed due diligence in pursuing development of the invention.

Deceased Inventor

An inventor who has died prior to filing a patent application or during the prosecution of a patent application.

Defensive Publication

A publication that prevents the grant of a patent to a competitor by placing information before the public so that it becomes prior art.

Dependent Claim

A claim which refers back to a preceding (dependent or independent) claim. Dependent claims are therefore more specific than independent claims. One purpose of a dependent claim is to help ensure that a more specific version of the claim survives if the broader independent claim on which it is based was found to be invalid.

Design Patent

A patent which covers the design or ornamentation of a non-natural object. Design patents are uncommon; most patents are utility patents.


An indication made by the applicant in a US international application filed under Patent Cooperation Treaty, as to the contracting state in which protection for an invention is sought.


A written description of an invention. Depending on the type of search being conducted the disclosure may be a relatively informal document, put together just for the purpose of conducting a patent search (this is often the case with a Novelty search), or the disclosure may actually be an existing patent (in the case of a Validity search).

Disclosure Statement

A statement disclosing an invention signed and forwarded by the inventor(s) to the USPTO. The USPTO accepts and preserves this disclosure for two years as evidence of the date of conception of an invention. It is not a patent application and its receipt in the USPTO will not become the effective filing date of any patent applicant subsequently filed.


During examination if the patent examiner finds that an application has more than one invention, they will request the applicant to choose one set of claims/invention to be proceeded with, which will be the original application. The other set of claims constitute a fresh application and would be considered a divisional application.

Doctrine of Equivalents

A legal concept which allows a patent owner to claim infringement, even if the Claims of said patent are not literally infringed, due to the very similar nature of the infringing behavior.

Double Patenting

An improper attempt to obtain more than one patent on the same invention or on an obvious variant of the same invention.


European Patent Office

Element of a Claim

A feature of an invention that correlates the feature with other features of the invention. The elements of a claim are usually numbered in a patent document.


This term is used by the European Patent Office to describe patent documents having the same priority dates otherwise called patent families.

Ex Parte

A legal proceeding that has no adversary present. This means that although a third party can request for a patent re-examination, he has no right to participate in the Patent Office's re-examination proceedings.


The process which a patent application undergoes to become a patent. Also referred to as "prosecution".


An employee of the USPTO or other patent office whose job it is to review patent applications, review the relevant prior art, and accept or reject the application. The examiners are also in charge of classifying approved patents into the appropriate classes/subclasses. Also called the primary examiner and sometimes assisted by an assistant examiner.

Exemplary Claim

The claim published in the Official Gazette of the USPTO.

Expirty Date

The date when a patent has run its full term and the invention is no longer protected by it.

Family Member

Multiple patents that are somehow related. This can happen when the USPTO requires that a single patent application be broken into several patents, or when a patent application that was filed in another country is filed elsewhere. The result is several patents that appear very similar, or even identical.

File Wrapper

The complete file of a patent application containing all related papers prepared by the Patent Office and the applicant during the patent prosecution. It is also called File History.

First to File

A system in which the first person to file a patent application will be awarded a patent. This system is used in all countries except the US.

First to Invent

A system used in the US in which the first person to invent an invention will be awarded a patent.

Forfeited Application

A patent application for which maintenance fee has not been paid within the prescribed period.

Government Interest

A field present in the USPTO database which describes the US Government's interest in the patent.

Grace Period

An interval (12 months) prior to the earliest patent application, during which time a disclosure of the invention will not destroy its novelty, provided that the disclosure is by, or authorized by the inventor.

Hand Search

Refers to a search where every patent in a class/subclass is quickly reviewed. This is considered more thorough than a keyword search by some, as there is no opportunity to miss patents due to incorrect choice of search terms.

INID Codes

Internationally agreed numbers that are used to identify bibliographic data and usually shown in brackets or circles. These numbers are consistent in every country and enables reading of important information on a patent document, even if one does not understand the language in which it is printed.

Independent Claim

A claim which does not refer back to any preceding claim, and therefore stands on its own.


An invention may infringe a patent if it is a copy of the invention covered by the patent, or if it performs the same function in the same manner and produces the same result.

Infringement Search

A search conducted for the purpose of determining if a given product or process would infringe upon any in-force patent claims.

Inter Parte

A term used in patent reexamination, where third parties have the right to request and fully participate in the Patent Office's reexamination proceedings.


A proceeding carried out by the Patent Office to determine who the first inventor is. This happens when two or more applications are filed by different inventors claiming essentially the same invention.

Invalidity Search

See Validity Search.


Any new article of manufacture, machine, composition, or process.


Acronym for the "Manual of Patent Examination Procedure". This is the guide used by USPTO examiners when prosecuting a patent, and can be a useful reference for technical questions on US patents.


A device used to accomplish a task.

Maintenance Fee

Renewal fees that need to be periodically paid to the Patent Office during the patent term in order to keep it force. Also called "Annuity" in some countries.

New Matter

Information that is not present in the original specification, claims or drawings and which an applicant attempts to add to a patent application.


The term used in US law to describe a requirement that an invention must meet to qualify for patentability. For an invention to be patentable it should not be obvious meaning that a person having ordinary skill in the art would not know how to solve the problem at which the invention is directed by using exactly the same mechanism.

Non-patent literature

Any documents that are not patents. Often used when describing portions of a patent search that review web sites, technical journals and databases, textbooks, etc.

Novelty Search

A patent search used to determine if a newly-conceived invention is different enough from prior art to allow patenting. Also called a Patentability Search.

Office Action

A written communication from the examiner of the US Patent Office stating the position of a pending patent application.

On-Sale Bar

A US law that prevents grant of patent if the subject of the patent application was on sale for more than a year before the priority date.

Opposition Proceedings

Legal proceedings carried out before an internal Patent Office tribunal, in which a third party raises objection to the grant of a patent.

Original Application

An application that is not a reissue application and may be the first filing or a continuing application.


Patent Cooperation Treaty. Members of the treaty can file a single international application to the World Intellectual Property Organization (WIPO) for seeking protection in all or any of the member states.

Parent Application

An earlier application of the inventor disclosing a given invention.

Paris Convention

A treaty adhered to by about 130 countries, which helps those who wish to obtain patent protection in more than one country. This treaty allows patent applicants a period of 12 months from their first filing (in their home country) to file subsequent applications in other countries for the same invention.


Right granted by the USPTO to prevent others from making, using, or selling an invention of the grantee.

Patent Pending

Indicates that a patent application has been filed. This does not necessarily mean that a patent will be granted.

Patentability Search

See Novelty Search.

Plant Patent

A patent covering certain types of plants. These patents are rare, and do not cover genetically engineered plants (which fall under the common Utility Patent).

Pre-Grant Publication

A patent application published 18 months from priority date.

Preliminary Examination

Short formal examination of an application to ensure that local minimum standards and legal requirements for filing have been met.

Prior Art

State of knowledge existing or available before the date of an invention.


A legal concept created by the Paris Convention wherein member states are entitled to patent protection from the date of first filing in any of the member states.

Pro Se Applicant

Term used to describe an independent inventor who has elected to file an application by himself without the services of a licensed representative.


Method for providing a useful result (such as a method for producing chemicals, or software which produces some tangible result). Processes can be covered by patents.


Prosecution is the name for the process through which a patent goes to be approved.

Provisional Application

A provisional patent application is a brief application which gives the inventor one year from date of filing the provisional application to file a full utility patent application.

Publication Level

A field present in the USPTO database to indicate publication level and which is only present for Reissue Patents and Defensive Publications. A single character 'E' is used for Reissue and 'H' for Defensive Publication.

Reads on

Means "is relevant to", as in "this piece of prior art reads on Claim 2 of the subject patent".


The process by which new evidence is presented to the USPTO concerning a previously-issued patent, and the USPTO examiners review the information to determine if the patent was issued in error.


The process by which errors are corrected in previously issued patents. The error is corrected, and the patent is reissued under a new patent number, with the format RE12345.


A ruling in an office action by a patent examiner, that one or more claims are not allowed.


Action taken by the Court or Patent Office to withdraw the rights of a proprietor to enforce the claims of a patent.

Right to Use Search

See Infringement Search.


Statutory Invention Registration. A method for disclosing an invention to the public so that others cannot claim to have originated the same invention. The SIR document looks like a patent, but does not grant any of the rights of a patent to the inventor.

Series Code

An identification number assigned by the US Patent Office to applications, which have received a filing date.
2 - earlier than 1-1-1948
3 - 1-1-1948 to 12-31-1959
4 - 1-1-1960 to 12-31-1969
5 - 1-1-1970 to 12-31-1978
6 - 1-1-1979 to 12-31-1986
7 - 1-1-1987 to 12-31-1992
8 - 1-1-1993 to 12-31-1997
9 - 1-1-1998 to current
29 - Designs applications (January 1993 on)

State of the Art Search

See Collection Search.

Statutory Period

The period within which a response is to be filed with the USPTO if abandonment of the application is to be avoided.


A category, organized by subject matter, into which patents are classified. Subclasses fall below classes in the patent organization hierarchy. Classes normally contain dozens or hundreds of subclasses.

Substantive Examination

Process carried out by the Patent Office, comparing the detailed contents of a patent application against the prior art, to determine patentability.

Technical Field

The field of art to which the invention relates.

Term Extension Notice

Sometimes the term of the patent is extended due to delays in the USPTO processing beyond certain limits. If the term is extended, it will be noted as a certain number of days of extension.

Term Restoration

Procedure to allow a proprietor to continue to enforce their claims, beyond the normal term of a patent, due to unavoidable loss of rights early in the patent-granting process.

Term of Patent

Subject to payment of fees, a patent shall be granted for a term beginning on the date on which the patent issues and ending 20 years from the date on which the application for the patent was filed in the US. If the application contains a specific reference to an earlier filed application or application, the term would be from the date on which the earliest such application was filed.

Terminal Disclaimer

A binding statement made with the Patent Office in a case where more than one patent has been obtained by the inventor on the same invention. The disclaimer will state that the later patent will expire at the same time as the former patent and the later patent will be enforceable only as long as both the patents are commonly owned.


United States Patent and Trademark Office, the government agency which grants patents in the U.S.


Uses are one class of invention covered by patents. For instance, a new use for a pre-existing device might be patentable.

Utility Patent

Covers inventions which function in a unique manner to produce a useful result.

Validity Search

A search conducted with the intent of finding prior art to invalidate a pre-existing patent. Also referred to as an Invalidity Search.


Action by patent applicant to terminate proceedings on their application.