In statistics, a player is credited with a plate appearance (denoted by PA) each time he completes a turn batting. A player completes a turn batting when:
- He is declared out before reaching first base, or
- He reaches first base safely, or
- He hits a fair ball which causes a third out on another runner (see left on base)
Thus, a batter does not have a plate appearance if, while he was at bat, the inning ended some other way (for example, a teammate on base is caught stealing for the third out).
Basically, "plate appearances" = at bats + some of the scenarios excluded from at bats such as base on balls, hit by pitch, sacrifice or catcher's interference which positively affect the offensive team.
In common terminology, the term "at bat" is sometimes used to mean "plate appearance" (for example, "he fouled off the ball to keep the at bat alive"). The intent is usually clear from the context, although the term "official at bat" is sometimes used to explicitly refer to an at bat as distinguished from a plate appearance.
The main use of the plate appearance statistic is in calculating the on base percentage, an alternative measurement of a position player's performance. It is also used to determine a player's eligibility for leadership in some offensive statistical categories, notably batting average.
Plate appearances are also used by scorers for "proving" a box score. If the game has been scored correctly, the total number of plate appearances for a team should equal the total of that team's runs, men left on base, and men put out.