Association football, commonly known as football or soccer, is a sport played between two teams of eleven players with a round ball. It is played by 250 million players in over 200 countries, making it the world’s most popular sport. Soccer is known as football throughout most of the world. In North America, however, the word soccer is used to avoid confusion with American football as played in the National Football League, or NFL. There are around 3.5 billion fans of football worldwide.