The Major League Baseball (MLB) is a professional baseball organization and the oldest major professional sports league in the world. As of 2022, a total of 30 teams play in Major League Baseball—15 teams in the National League (NL) and 15 in the American League (AL)—with 29 in the United States and 1 in Canada.

The NL and AL were formed in 1876 and 1901, respectively. Beginning in 1903, the two leagues cooperated but remained legally separate entities until 2000 when they merged into a single organization led by the Commissioner of Baseball.