What is Major League Baseball? Major League Baseball is the oldest of the four major professional sports leagues in the USA and Canada. Initially, there were two separate entities: First was the National League in 1876. Then the American League was formed in 1901 to compete against it. In 1903, they decided to combine their efforts and establish control of organized baseball in North America leading to the first modern World Series. However, the leagues still operated as separate entities until 2000, when they merged into a single organization led by the Commissioner of Baseball: Bud Selig. Both the leagues (AL and NL) are divided into 4 divisions: North, East, South and West. The League Division Series consists of four best-of-5 games played by 8 teams (four teams from each league). The winners of both the Divisions (ALDS and NLDS) then move on to the Championship Series to play a best-of-7 series. The world series is played by the winners of the Championship series and that too is a best-of-7 series. And the winner is crowned the best team in America!