Overview
Major League Baseball (MLB) is the premier professional baseball league in North America. It is widely regarded as the top level of the sport globally and features 30 teams: 29 based in the United States and one in Canada, the Toronto Blue Jays. Teams are divided between two constituent leagues, the American League and the National League, which together form MLB's competitive and business structure.
Structure and season
The MLB calendar includes a long regular season during which teams play a fixed schedule of games to establish standings. The season culminates in a postseason tournament that determines the league champions and ultimately the World Series winner, MLB's annual championship series. The postseason format has evolved over time to include division winners and one or more wild-card teams, with additional rounds of short series to decide who advances.
Rules and distinctions
While most playing rules are shared across MLB, the two leagues historically had distinctive practices. The American League adopted the designated hitter role to allow a player to bat in place of the pitcher, a notable difference from the National League for many decades. Interleague play—regular-season games between teams from the two leagues—now occurs regularly, and rules have continued to converge in recent years.
History and development
MLB traces its roots to 19th- and early 20th-century professional leagues. The National League dates from the 1870s and the American League emerged as a major circuit around the turn of the century; their relationship evolved into the modern organized structure. Over the next century, the sport expanded geographically and commercially, adding franchises and developing national media coverage that helped cement baseball's place in American and Canadian sports culture.
Importance and cultural role
Beyond competition, MLB is influential in sporting culture, statistics, and business: it hosts an annual All-Star exhibition, fosters youth and community programs, and serves as a major source of historic records and milestones in the sport. For official information, schedules and statistics, MLB maintains its central site at the league's official website.
Further reading and resources
- League organization and team directories: see the American and National League pages via official outlets.
- Season formats and postseason history: summaries and timelines provide context for rule changes and playoff expansions.
- Historical overviews: accounts of early professional baseball and franchise histories trace the sport's growth.