BaseballBaseball is a popular bat-and-ball game played mainly in the United States. It is a professional sport, and the most popular league in the United States is Major League Baseball (MLB). MLB features 30 teams, split into two 15-team leagues, the National League (NL) and the American League (AL). Each team plays 162 games during the regular season, which typically runs from April through the beginning of October. The MLB postseason includes the World Series, a best-of-seven tournament between the AL and NL champions, and the two Wild Card Series. The Wild Card Series pits two wild card teams that didn't win their division against each other. The postseason culminates with the World Series, where the AL and NL champions battle for the crown. Popular teams in the MLB include the New York Yankees, Boston Red Sox, and the Chicago Cubs. Popular MLB players include Mike Trout, Mookie Betts, and Aaron Judge. Baseball has its roots in the mid-1800s and has been played in roughly its current form since 1903. The sport has seen several changes since then, most notably the integration of Jackie Robinson, who broke the color barrier in 1947. MLB teams are now located all over the United States and Puerto Rico, and baseball is a popular pastime all around the globe. Today, MLB features some of the best and most talented players in the world, and the sport continues to be a hallmark of American sports.