First played in 1903, the World Series features the winners of the American League and National League competing against one another to crown a Major League Baseball champion.

While the number of teams competing in the MLB postseason has grown over the years, going from two to 12 (six in each league), the World Series format has essentially gone unchanged for more than a century outside of some tweaks to determine which team has home-field advantage.

The current format gives the team with the best regular-season record the advantage, which is the most fair way to do things. Up until 2002, home-field advantage alternated from year to year between the AL and NL. And from 2003 to 2016, the winner of the MLB All-Star Game was the deciding factor, which was heavily criticized.

How many games are in the World Series?

As it's been since 1922, the World Series is contested using a best-of-seven format, meaning the first team to win four games takes the title. Not every Fall Classic, of course, goes all seven games.

The last World Series to go the distance was in 2019 when the Washington Nationals defeated the Houston Astros.

Under the current 2-3-2 format, the higher seed hosts Games 1, 2, 6, and 7 of the World Series, while the lower seed hosts Games 3, 4, and 5.

Prior to 1922, four editions of the World Series were contested using a best-of-nine format, including the first modern edition in 1903. That year, the AL champion Boston Americans, who you now know as the Boston Red Sox, defeated the Pittsburgh Pirates five games to three.

The best-of-nine format returned in 1919 for the infamous series between the Cincinnati Reds and the Chicago White Sox, which featured the "Black Sox" scandal, and was used for three years.