The ALCS stands for the American League Championship Series. It is a best-of- seven playoff series in Major League Baseball (MLB) that determines the winner of the American League pennant. The team that wins the ALCS advances to the World Series to face the champion of the National League. The ALCS began in 1969 and was originally a best-of-five series, changing to a best-of-seven format in 1985. Since 1995, the ALCS is contested between the winners of the American League Division Series (ALDS).