Rules of NFL Football in America: by Freddie Brister

NFL football is a competitive team sport known for mixing strategy with physical play. The object of the game is to score points by advancing the ball into the opposing team's end zone.
A standard football game consists of four 15-minute quarters, with a half-time intermission after the second quarter.
A down ends, and the ball becomes dead, after any of the following: the player with the ball is forced to the ground or has his forward progress halted by members of the other team, a forward pass goes out of bounds or touches the ground before it is caught, or if a team scores.
You can score by getting a safety, field goal, or touchdown. If you get a touchdown, you have the choice of kicking the extra point or going for a two point conversion.
Fouls are punished with penalties against the offending team. Most penalties result in moving the football towards the offending team's end zone.
The offensive line consists of five players whose job is to protect the passer and clear the way for runners by blocking members of the defense.
The quarterback receives the snap from the center on most plays. He then hands or tosses it to a running back, throws it to a receiver or runs with it himself.
Running backs line up behind or beside the QB and specialize in running with the ball. They also block, catch passes and, on rare occasions, pass the ball to others or even receive the snap.
Wide receivers line up near the sidelines. They specialize in catching passes, though they also block for running plays or downfield after another receiver makes a catch.
Tight ends line up outside the offensive line. They can either play like wide receivers or like offensive linemen.
At least seven players must line up on the line of scrimmage on every offensive play.
The defensive line consists of three to six players who line up immediately across from the offensive line.
Behind the defensive line are the linebackers. They line up between the defensive line and defensive backs and may either rush the quarterback or cover potential receivers. Their main job is to cover the run up the middle.
The last line of defense is known as the secondary, comprising at least three players who line up as defensive backs, which are either cornerbacks or safeties. They cover the receivers and try to stop pass completions. They occasionally rush the quarterback. However, this leaves the field wide open for passing.
The units of players who handle kicking plays are known as special teams. Three important special-teams players are the punter, the kicker, and the long snapper.
Because the game stops after every down, giving teams a chance to call a new play, strategy plays a major role in football.
To stop the offense from advancing the ball, the defense must tackle the player with the ball by knocking or pulling him down. Tacklers cannot kick or punch the runner. They also cannot grab the face mask of the runner's helmet or lead into a tackle with their own helmet.