A pinch hitter is a batter used as a substitute for another batter. A pinch hitter only comes into the game when the batter whose turn he is taking is due to bat. At that time, he is "announced into the game"; the batter which he replaced is out of the game for good. If a pinch hitter is in the on-deck circle but the inning ends before he comes to bat, he is not considered to have been announced into the game and can be used at a later point of the game. If a substitute player is already in the game, having come in earlier as a defensive substitute or as a pinch runner, he is not considered to be a pinch hitter when his turn to bat comes. The usual abbreviation for a pinch hitter is PH.
Pinch hitters are used principally in two situations: to replace a weak hitter (often the pitcher, although a weak-hitting defensive specialist can also be a target), or to gain a platoon advantage. In some instances, a manager will send a pinch hitter to execute a specific play, such as a sacrifice bunt.
When the pinch hitter's team takes the field the next half-inning, the pinch hitter can either:
- (a) take the defensive position of the player for which he pinch hit;
- (b) take another position on the field, with other defensive substitutions being made to ensure that all defensive positions are filled; or
- (c) be in turn replaced by a defensive substitute.