MLB is the highest level of professional baseball in the United States and Canada, consisting of teams that play in the National League and the American League. The two leagues merged in 2000 into a single MLB organization led by the Commissioner of Baseball after 100 years as separate legal entities. MLB constitutes one of the major professional sports leagues of the United States and Canada.MLB has many famous teams, such as baltimore orioles, chicago white sox, los angeles dodgers, san francisco giants and so on.It is composed of 30 teams—29 in the United States and one in Canada. With the International Baseball Federation, MLB also manages the World Baseball Classic. Brian McCann, Dustin Pedroia, Aramis Ramirez, and Brandon Phillips are famous MLB players.