Football is the most popular team sport in the world. Millions of people go to football stadia each year to watch their favourite teams and billions more follow the game on television.
The game is played on a rectangular grass or artificial turf field, with a goal at each end of the field. The object is to score by manoeuvring the ball into an opposing goal, defended by a goalkeeper.
Players are divided into several categories, with strikers concentrating on scoring goals, defenders preventing their opponents from scoring, and midfielders combining these functions. There are also special positions for specialised roles such as left and right wingers.
Line of Scrimmage: An imaginary line on the ground marking the line where each team must start its play. Teams cannot cross the line of scrimmage until a play has begun; the ball is placed at that point on the field.
First Down: A mark 10 yards from the line of scrimmage, displayed on television broadcasts as a yellow line. On each of the first three downs a player may run, catch a pass, or kick the ball to change possession.
Lateral: A pass made to a player that is parallel to or behind the player making the pass. This is distinguished from forward passes, which must be made to a player in the same direction as the ball.
Safeties: If a defensive player is tackled in the opponent’s own end zone, the player receives two points for the team.