Original: It is an active member of USA Basketball (USAB), which is recognized by the International Basketball Federation as the National Governing Body (NGB) for basketball in the United States. The NBA is one of the four major North American professional sports leagues, which include Major League Baseball (MLB), the National Football League (NFL), and the National Hockey League (NHL).
Simplified: The National Basketball Association (NBA) is the world's top men's professional basketball league and one of the major professional sports leagues of North America only.