The Oakland Athletics, often referred to as the A's, are an American professional baseball team based in Oakland, California. They compete in Major League Baseball (MLB) as a member club of the American League (AL) West division. The team plays its home games at the Oakland–Alameda County Coliseum.
One of the American League's eight charter franchises, the team was founded in Philadelphia in 1901 as the Philadelphia Athletics. They won three World Series championships from 1910 to 1913 and back-to-back titles in 1929 and 1930. The team's owner and manager for its first 50 years was Connie Mack and Hall of Fame players included Chief Bender, Frank "Home Run" Baker, Jimmie Foxx, and Lefty Grove. The team left Philadelphia for Kansas City in 1955 and became the Kansas City Athletics before moving to Oakland in 1968. They won three consecutive World Championships between 1972 and 1974, led by players including Catfish Hunter, Reggie Jackson, ace reliever Rollie Fingers, and colorful owner Charlie O. Finley. After being sold by Finley to Walter A. Haas Jr., the team won three consecutive pennants and the 1989 World Series behind the "Bash Brothers", Jose Canseco and Mark McGwire, as well as Hall of Famers Dennis Eckersley, Rickey Henderson and manager Tony La Russa.
They have won nine World Series championships, the third-most of all current MLB teams. The 2017 season was the club's 50th while based in Oakland.