American football, known in the United States simply as football and sometimes as gridiron outside the United States and Canada, is a sport played between two teams of eleven. The objective of the game is to score points by advancing the ball (actually a prolate spheroid) into the opposing team's end zone. The ball can be advanced by running with it or throwing it to a teammate. Points can be scored by carrying the ball over the opponent's goal line, catching a pass thrown over that goal line, kicking the ball through the opponent's goal posts or tackling an opposing ball carrier in hi...