There are 32 teams in the Major League Baseball.  There are 2 Leagues and in each league there are 5 Divisions.  that is how they have the All-Star Game.  National vs American.  That is also how they do the playoffs.  In the World Series it is a National team against a American.  The American team is usually better than the National team.  In the All-Star Game American have won 5 years in a row.  Now who ever wins the All-Star game gets home field advantage in the playoffs and in the World Series.  The two leagues are fun to watch because it is always a good game.  Some of the teams in the American league are New York Yankees, the Mets, Mariners, Red Sox, Devil Rays, and the Twins.  The National teams are Pirates, Cubs, Reds, Cardinals,  Astros, Phillies, and the Giants.  It is also fun to watch the teams in the same league play each other.  Having two Leagues make the MLB very intersting.