In baseball, a starting pitcher (also referred to as the starter) is the pitcher who delivers the first pitch to the first batter of a game. A pitcher who enters the game after the first pitch of the game is a relief pitcher. A starting pitcher in professional baseball usually rests three or four days after pitching a game, before pitching another. Therefore, most professional baseball teams have four or five starting pitchers on their rosters. These pitchers, and the sequence in which they pitch, is known as the rotation. In modern baseball, a five-man rotation is most common.