Football is the most popular sport in the world. A football game is when you move the ball with your feet, your chest, or your head, but not your hands. The goalkeeper can use his or her hands to catch or touch the ball. The goalkeeper's job is to try to keep the opposing team from putting the ball into the net. The object of the game is to score a point by kicking the ball into the goal of the other team. It is played by 2 teams of has 11 players each, including a goal keeper for each team. In the Olympics the game lasts 90 minutes with two halves of 45 minutes each and a 15-minute half-time break. There is one referee and two assistant referees. The assistants run along the touch lines on either side of the field to help the referee. The referee makes sure the players are following the rules and blows his whistle to signal a foul. Soccer shorts, shirt, tall socks, shin guards, soccer cleats (special shoes with short spikes on the bottom to keep the player from slipping on the grass is needed for player who play football. A football game is conducted on a rectangular grassy area 115 yards long x 75 yards wide. It is called a pitch. The filed marked by touch lines on the outside and goal lines surrounding the goal areas. The field's center is a circle with a diameter of 10 yards. The area in front of the goalposts is divided into the goal neighboring the goalpost and the penalty area extending toward the center.