What is the MLB?
MLB, or Major League Baseball, is the top professional baseball league in North America, with 30 teams in the American League and National League. Its season ends with the World Series.
The National League was founded in 1876, making it the oldest professional sports league still operating in the United States. The American League began in 1901. The two leagues began playing each other in the World Series in 1903. Today, 29 teams are in the US and one, the Toronto Blue Jays, is in Canada.
Each team plays 162 games during the regular season, which runs from late March or early April to late September. Twelve teams make the playoffs. In 2023, MLB introduced a pitch clock and other rule changes that shortened games and increased action.
Champions
The New York Yankees have won the most World Series titles, with 27. In 2026, the Milwaukee Brewers won their first championship. Famous players include Babe Ruth, Jackie Robinson, who broke baseball's color barrier in 1947, Hank Aaron and Shohei Ohtani.
Did You Know?
Every player in MLB wears number 42 on April 15, Jackie Robinson Day, the only number retired across the entire league.