To the uninitiated it looks like armoured mayhen, but actually, like basketball, each player has a specific task and for play to succeed all players must co-ordinate their actions. Perhaps the game is best understood as contact chess in which players are moved to gain maximum advantage.
The game is played on a rectangular field 100 yards long x approx. 53 yds wide, with 10 yard scoring zones (endzones) at each end of the field. The team with the ball has 4 downs (or plays) to move the ball 10 yards. If they succeed, either by carrying the ball or catching a thrown pass, they earn a first down, which starts another series of four downs. If they fail, then the ball is handed over to the other team where it ended at the conclusion of their 4th play.
So 3rd and 2 means this is a teams third attempt and they still have 2 yards to get. On 4th and 2 they’d probably punt (kick) the ball away rather than risk handing over to the other team in good field position.
To help those watching (and playing) the game to know the status of down and distance required, a set of markers are held on the side of the field. The chains are simply two markers linked by a chain 10 yards long and the downmarker is simply a marker which displays the numbers 1 through 4. So at a glance it is easy to see which play the team with the ball is on and how far they have to gain a first down (the distance from the downmarker to the marker at the end of the 10 yard chain). When a team advances the ball past the second marker, the referee signals a first down by pointing his arm in the direction they are moving and the chains and downmarker are repositioned for the next series of plays.
Consists of…
Touchdowns (6 points) – scored when the team with the ball runs or passes it into the opponent’s end zone.
Field Goals (3 points) – scored when the offense kicks the ball off the ground (usually held in place by a team mate)
between the goal post and above a cross bar set 10 feet from the ground).
Extra Points (1 or 2 points) – after a touchdown has been scored, the offense are given one play from the opponen’s 3
yard line to score additional points. If they run or pass the ball into the endzone they get 2
additional points, or if they score by kicking the ball through the uprights (like a field goal) they
get 1 additional point.
Safety (2 points) – a fairly rare occurrence. The points are awarded to the defensive team if they down the ball carrier,
or force him out of bounds in his own endzone.