The starting pitchers for any game are the two pitchers that started the game for each team. Starting pitchers are generally the best five pitchers on each team. They'll begin and pitch for the majority of the games you play. The starters selected will rotate from game to game depending on their condition. On an average rotation, the fifth starter will get about two thirds as much work as any of the first four.
In baseball or softball, a starting pitcher, often abbreviated as starter, is the pitcher who pitches 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.