The American League Championship Series (ALCS) is a best-of-seven playoff and one of two League Championship Series comprising the penultimate round of Major League Baseball's (MLB) postseason. It is contested by the winners of the two American League (AL) Division Series. The winner of the ALCS wins the AL pennant and advances to the World Series, MLB's championship series, to play the winner of the National League's (NL) Championship Series. The ALCS began in 1969 as a best-of-five playoff and used this format until 1985, when it changed to its current best-of-seven format.