Twist serve
A twist serve (or American twist) is a type of serve in tennis. It is also called a kick serve.
A twist serve is thrown somewhat behind the server's head, then hit with top spin that makes the ball go in an angled arc over the net. Upon bouncing, it jumps high to the side in the direction of the server's racquet arm. If a right hander hits a twist serve to the ad (backhand) court, it will jump out away from the center of the court.
The twist serve, when mastered, is generally safer than the flat serve. The arc of the ball provides extra margin for error as it is higher going over the net and then drops quickly into the service box. It is therefore effective as a second serve to reduce double faults.
Although slower than the flat serve, the twist serve has many tactical advantages, for example to pull an opponent off the court to employ a serve-and-volley tactic, or to bounce the ball higher than the opponent's comfort zone.
Its major drawback is that it is primarily effective against opponents of somewhat lesser quality. Highly skilled players can step into the high bounce of the twist serve and chip it back over the net with great effectiveness. For this reason it is not used as much by world-class players as it is by intermediate-level players.