Major League Baseball (MLB) is the highest level of play in professional baseball in the world. More specifically, Major League Baseball ("MLB") refers to the entity that operates North America's two top leagues, the National League and the American League, by means of a joint organizational structure which has existed between them since 1920. MLB is one of the major professional sports leagues of North America.

Major League Baseball is governed by the Major League Constitution, an agreement that has undergone several incarnations since 1920, with the most recent revisions being made in 2001. Major League Baseball, under the direction of its Commissioner, hires and maintains the sport's umpiring crews, and negotiates marketing, labor, and television contracts. The 'closed shop' aspect of MLB effectively prevents the yearly promotion and demotion of teams into the Major League by virtue of their performance.

MLB also maintains a unique, controlling relationship over the sport, including most aspects of minor league baseball. This is due in large part to a 1922 U.S. Supreme Court ruling in Federal Baseball Club v. National League which declared baseball is not considered interstate commerce (and therefore not subject to federal antitrust law), despite baseball's own references to itself as an "industry" rather than a "sport."

The production/multimedia wing of MLB is New York-based MLB Advanced Media, which oversees MLB Productions (video), as well MLB.com and all 30 of the individual teams' websites. It's charter states that MLB Advanced Media holds editorial independence from the League itself, but it is indeed under the same ownership group and revenue-sharing plan.

Current Major Leagues

The Major League season generally runs from early April through the end of September. Players and teams prepare for the season in spring training, primarily in Florida and Arizona, during February and March.
 

Teams and schedule

In all there are 30 teams in the two leagues: 16 in the older National League ("NL") and 14 in the American League ("AL"). Each has its teams split into three divisions grouped generally by geography. They are (number of teams in each division in parenthesis): NL East (5), NL Central (6), NL West (5), AL East (5), AL Central (5) and AL West (4).

A Major League season normally lasts from the beginning of April to the end of September. Each team's regular season consists of 162 games, a duration established in 1961. From 1904 to 1960, except for 1919, a 154-game schedule was played. Shortened seasons were played in 1918 due to the outbreak of World War I, and in 1972, 1981, 1994 and 1995 due to player strikes and lockouts. Games are played predominantly against teams within each league through an unbalanced schedule which heavily favors intra-divisional play. In 1997 Major League Baseball introduced inter league play, which was criticized by the sport's purists but has since proven very popular with most fans.

For a detailed history of the length of the regular season, keep in touch with Sports Den.