In baseball, an assist is a defensive statistic, baseball being one of the few sports in which the defensive team controls the ball. An assist is credited to every defensive player who fields or touches the ball prior to the recording of a putout, even if the contact was unintentional. For example, if a ball strikes a player's leg and bounces off him to another fielder, who tags the baserunner, the first player is credited with an assist. A fielder can receive a maximum of one assist per out recorded. An assist is also credited if a putout would have occurred, had another fielder not committed an error. For example, a shortstop might field a ground ball cleanly, but the first baseman might drop his throw. In this case, an error would be charged to the first baseman, and the shortstop would be credited with an assist.

In baseball statistics, a putout (PO) is awarded to a defensive player who records an out by one of the following methods:Tagging a runner with the ball when he is not touching a base Catching a batted or thrown ball and tagging a base to put out a batter or runner Catching a thrown ball and tagging a base to record an out on an appeal play Catching a third strike Catching a batted ball on the fly Being positioned closest to a runner called out for interference