The World Series is the annual championship series of Major League Baseball (MLB), played between the American League and National League champions since 1903. The winner of the World Series championship is determined through a best-of-seven playoff and awarded the Commissioner's Trophy As the series is played in October, Major League Baseball also refers to it as the 'Fall Classic'. The most recent World Series was won by the St. Louis Cardinals, who defeated the Texas Rangers in seven games in 2011. The New York Yankees of the American League have played in 40 World Series and won 27, the Oakland/Philadelphia Athletics have played in 14 and won nine, and the Boston Red Sox have played in 12 and won seven, including the first World Series. In the National League, the St. Louis Cardinals have played in 18 and won 11, while the San Francisco/New York Giants and Los Angeles/Brooklyn Dodgers have both appeared in 18 and won six.