In tennis, an ace is when you get a point on one swing. There are two types of commonly referred to aces: Service Ace, and Return Ace. A service ace (or simply ace), is when the ball is not returned from the serve. These are very difficult to accomplish.

A Return ace is when the ball is returned from the serve in such a way that the server cannot volley the ball back to the opponent. These are tough, and are definate crowd pleasers in most high tension matches.