american football

 American football, known in the United States as football, is a sport played
by two teams of eleven players on a rectangular field 120 yards long by 53.3
yards wide with goalposts at each end. The offense attempts to advance an oval
ball down the field by running with or passing it. They must advance it at
least ten yards in four downs to receive a new set of four downs and continue the
drive; if not, they turn over the ball to the opposing team. Points are scored by
advancing the ball into the end zone for a touchdown, kicking the ball through the
opponent's goalposts for a field goal or by the defense tackling the ball carrier
in the offense's end zone for a safety.
American football evolved from rugby and association football. The first game was
played on November 6, 1869. A set of rule changes drawn up from 1880 onward by Walter
Camp established the snap, eleven-player teams and downs. Later rule changes legalized
the forward pass, created the neutral zone and specified the width of the football.
American football is the most popular sport in the United States and the National
Football League's championship game, the Super Bowl, is among the most-watched
sporting events in the world.