THE BASICS: The closest similarity is with rugby, in that points are usually scored either by touchdowns (worth six points), which can be converted for single extra points, or by kicking the ball between the posts from distance (field goals, worth three points). But it is rugby crossed with Rollerball and WWF wrestling, and the personnel usually changes completely depending on whether a team is attacking or defending.

THE OFFENSE: The team in possession of the ball is allowed four attempts (“downs”) to advance the ball a minimum of ten yards, in which case they retain possession and gain another four downs. The ball is either carried by a running back or thrown to a receiver by the quarterback, who decides on the type of play beforehand. If the offense can run the ball into the endzone, or if a receiver catches a thrown ball there, a touchdown is scored. If, on the fourth down, a team feels it cannot score a touchdown, it may attempt a field goal. If the offense fails to advance the ball ten yards after four downs, possession is yielded to their opponents.

THE DEFENSE: The defense must prevent the offense reaching their endzone, either by blocking or tackling a player carrying the ball, ripping the ball away from an opponent, intercepting a thrown ball, or preventing the quarterback from throwing. Four players (“the secondary”) will usually drop deep to attempt interceptions. The defensive line, physically the strongest defenders, attempt to break through the “offensive line” of equally strong attackers guarding the quarterback. Three or four versatile “linebackers” will fill any defensive role required – tackling runners, blocking, or attempting to “sack” (ground) the quarterback.

A game lasts one hour, which is divided into four quarters. Two periods of sudden-death overtime are played if the scores are tied after 60 minutes. Only time when the ball is in play counts.