Football, also known as soccer, is the world's most popular sport played between two teams of 11 players trying to get a ball into the opposing goal. It has over 250 million players globally and billions more fans. The basic rules are that teams can only use their feet, torso, head or legs to move the ball into the opponent's net within two 45-minute halves. The international governing body FIFA oversees competitions like the World Cup held every four years.