Once a patent application is filed, it enters the "prosecution" stage, during which it is examined by the Patent Examiner, who often challenges the originally-filed claims using various alleged prior art references. Via the Patent Attorney's skilled rebuttal, argument, amendment, and/or negotiation with the Examiner, the application can emerge from prosecution as an issued patent.

Along the way, the application might be amended and/or re-filed (keeping the benefit of its original filing date). In some cases, a final decision of the Examiner might be appealed, if appropriate. In a small minority of situations, the Applicant might decide to abandon further prosecution of the application. There are numerous other contingencies possible, thereby making a detailed explanation of the prosecution stage rather long and tedious.

The general process for prosecuting a patent application is:

1. The USPTO checks the filed application for conformance with numerous formalities.

2. Once all formalities are met, the USPTO sends it to an "Art Unit", which assigns the application to one of its many Examiners.

3. After a substantial delay (typically 9 to 30 months while the Examiner addresses a mountain of earlier-filed applications), the Examiner performs a search for prior art publications (typically published patents and patent applications) that reasonably relate to the claims of the filed application.

4. The Examiner prepares and mails an Office Action explaining why the Examiner believes the claims to be unpatentable.

5. The Patent Attorney reviews the Office Action, and with input from the inventors (if necessary), carefully prepares a Response to the Office Action. The Response might rebut the Examiner's approach, amend the specification, drawings, and/or claims, and/or present legal and/or technical arguments challenging the Examiner's position. Any written communication with the USPTO is carefully scrutinized to avoid providing potential "ammunition" to later opponents of the patent (whether licensees or litigants).

6. Prior to filing the Response, the Patent Attorney sometimes "interviews" the Examiner, either telephonically or in-person, to better explain the invention and/or claims, to better understand the Examiner's position, and/or to build rapport with the Examiner (thereby potentially smoothing future communications).

7. Typically, after several rounds of Office Actions and Responses, the Examiner becomes comfortable with the claims and issues a "Notice of Allowance and Issue Fee Due".

8. Assuming that the allowed claims and reasons for allowance are acceptable, the required Issue Fee is paid. Quite frequently, another patent application is filed that describes and claims various improvements to the original patent application. This "continuation" application should be filed no later than the date the Issue Fee is paid on the allowed "parent" application.

9. The USPTO issues, publishes, and mails a United States Patent, complete with gold seal and red ribbon.