A more thorough explanation:

The Federal Rules of Appellate Procedure are a set of rules that govern how appeals are handled in the United States courts of appeals. These rules apply to appeals from lower courts, some federal-agency proceedings, and applications for writs.

For example, if someone is convicted of a crime in a lower court and wants to appeal the decision, they would need to follow the Federal Rules of Appellate Procedure. These rules would dictate how the appeal is filed, what documents need to be submitted, and how the case will be heard in the appeals court.

Another example would be if a person is seeking to challenge a decision made by a federal agency, such as the Environmental Protection Agency. The Federal Rules of Appellate Procedure would apply to this situation as well, outlining the process for appealing the decision to a higher court.

Overall, the Federal Rules of Appellate Procedure are important because they ensure that appeals are handled fairly and consistently across the United States courts of appeals.