In tennis, a point won directly from a legal serve is called an ace.
For a serve to count as an ace, it must land in the correct service box, or on one of its boundary lines, and the receiver must not touch it. Because the receiver never makes contact, the server wins the point immediately after the ball’s legal bounce.
Aces are most common on first serves, when players can use greater speed and riskier placement. Servers often target the corners of the service box or aim wide to pull the receiver away from the court’s center. A powerful serve is not automatically an ace: if the opponent gets a racquet on it, even weakly, it becomes an ordinary serve rather than an ace.
An ace also differs from a service winner, in which the receiver touches the serve but cannot return it effectively. A double fault is the opposite kind of service outcome: two faults give the point to the receiver.