In baseball, a pitch is the act of throwing a baseball toward home plate to start a play. The time of pitch is that instant when the pitcher (P) has begun his pitching motion and, by the rules, has committed himself to throwing the pitch. This instant thus occurs before the pitcher (P) actually releases the ball. Once a pitcher (P) commits himself to throwing a pitch, it is illegal for him to return to his set. If that happens, he is charged with a balk, and any baserunners are allowed to advance a base.