American football, known in the United States and Canada simply as football, is a competitive team sport known for its
physical roughness despite being a highly strategic game. The object of the game is to score points by advancing the football
into the opposing team's end zone. The ball can be advanced by carrying it, throwing it, or by handing it from one teammate
to the other. Points can be scored in a variety of ways, including carrying the ball over the goal line, throwing the ball
to another player past the goal line or kicking it through the goal posts on the opposing side. The winner is the team with
the most points when the time expires and the last play ends.
Advancing the ball in American football resembles the six-tackle rule and the play-the-ball in rugby league. The team that
takes possession of the ball (the offense) has four attempts, called downs, to advance the ball 10 yards towards their opponent's
(the defense's) end zone. When the offense gains 10 yards, it gets a first down, which means the team has another set of four
downs to gain yet another 10 yards or score with. If the offense fails to gain a first down (10 yards) after 4 downs, possession
of the ball is given to the opposing team.
Except at the beginning of halves and after scores, the ball is always put into play by a snap. Offensive players line up
facing defensive players at the line of scrimmage (the position on the field where the play begins). One offensive player,
the center, then passes (or "snaps") the ball between his legs to a teammate, usually the quarterback.
Players can then advance the ball in two ways: By running with the ball, also known as rushing. One ball-carrier can hand
the ball to another; this is known as a handoff. OR; By throwing the ball to a teammate, known as a forward pass or as passing
the football. The forward pass is a key factor distinguishing American and Canadian football from other football sports. The
offense can throw the ball forward only once on a play and only from behind the line of scrimmage. The ball can be thrown,
pitched, or tossed sideways or backwards at any time. This last type of pass is known as a lateral and is less common.