A more thorough explanation:

An advisory office action is a communication from a patent examiner to a patent applicant. It is usually sent to explain why an application has been denied. This type of communication is issued by the United States Patent and Trademark Office.

There are two types of office actions: first office action and final office action. The first office action is the initial reply from the patent examiner to the patent application. If the examiner rejects most or all of the claims, it is called a shotgun rejection. The applicant must respond to the examiner's reasons for rejection, amend the claims, or both to avoid abandoning the prosecution.

The final office action is the examiner's determination that the application is not allowable. The applicant can file a continuation application, appeal the decision, or request continued prosecution.

An advisory office action is issued after a final office action. It addresses the status of an amendment made in the applicant's response to the final rejection, indicates the status of the claims for appeal, addresses an affidavit or exhibit, or responds to a request for reconsideration.

• An applicant receives a final office action stating that their patent application has been denied. They respond with an amendment to the claims. The examiner then issues an advisory office action to address the status of the amendment and the claims for appeal.
• Another applicant receives a first office action with a shotgun rejection. They respond by amending the claims. The examiner issues a second office action, which is not an advisory office action, to review the amended claims.

These examples illustrate the different types of office actions and how they are used in the patent application process. The advisory office action is specifically used to address issues that arise after a final office action has been issued.