Would it surprise you to learn that association football, or soccer, is the world’s most popular sport played by 250 million players in 200 different countries? If you didn’t already know, there are three professional soccer leagues that are part of the United States Soccer Federation (USSF or U.S. Soccer). The top level league is Major League Soccer (MLS) and consists of 24 teams. In these soccer trivia questions and answers, you’ll learn more about this sport in terms of players, teams, seasons, playoffs, and the FIFA World Cup.