Major League Baseball (MLB) is the highest level of play in North American professional baseball. Founded in 1869, it is composed of 30 teams. Each team in the league has a manager, who is responsible for team strategy and leadership on and off the field. Assisted by various coaches, the manager sets the line-up and starting pitcher before each game, and makes substitutions throughout the game. In early baseball history, it was not uncommon for players to serve as player-managers; that is, they managed the team while still being signed to play for the club. In the history of MLB, there have been 221 player-managers, 59 of whom are in the National Baseball Hall of Fame.