In soccer, players other than the goalkeepers may not touch the ball with their hands while in bounds. Teams must have at least seven players to start a match and may not field more than 11 players at a time. The referee has full and final authority to enforce rules.
The Federation Internationale de Football Association is soccer's governing body and sets the laws of the game. There are currently 17 laws for soccer, which FIFA publishes in an annual guide. The first two govern the size of the field and the size and pressure of the ball. Laws five and six define the responsibilities and authority of the referees and linesmen. The remaining laws regulate players and play.
Play begins with a kickoff at center field and continues until one team scores a goal, the ball goes out of bounds or the referee stops play. If one team sends the ball out of bounds, the referee awards the ball to the opposing team and a member of that team throws the ball in to resume play. If the referee stops play due to a player's infraction, he awards a direct or indirect free kick to the other team, depending on the nature of the infraction. The referee may give a player a yellow card to caution him regarding serious misconduct or a red card to expel him from the game for violent behavior, serious foul play or receipt of a second yellow card during the same match.