Credito

Field, the game is played on a rectangular field 120 yards long by 53 yards wide. Yard lines cross the field every 5 yards, and are numbered from each goal line to the 50-yard line, or midfield.Each team owns half of the field (they change sides every fifteen minutes of the playing time). The goal line is called the "zero yard line". The teams try to advance the ball into the end zone theopponent's goal line and to score a touchdown. Each end zone has the goal posts, in form of a big letter H. These parts of the field are used only when a team wants to produce a field goal or in thecase when the team decides to get an extra point after touchdown scoring. To score an extra point or a field goal, the ball should go over the bar and between the vertical posts.

The teams are dividedin different groups or sub-teams as, offensive team, defensive team and special teams. They can play 11 players by team.

Kick-offs. The referee throws a coin to decide which team takes the ballfirst. Offense is the name of the team that gets the ball; the other team is called defense. An American football game lasts in theory an hour, but in fact, it takes about 3 hours of playing, since theplaying clock is frequently stopped for different reasons. The playing time is divided in quarters - 15 minutes each. The teams only change sides at the end of the third and first quarters. Theplayers have a 20 minutes break. The team that lost in the coin toss before the game, gets the ball first after the kick-off.

Scoring, because the game's goal is to achieve a higher score than the rivalteam. The team can get six points as a result of a touchdown. After a touchdown, the team attempts a extra conversion. The ball is placed at the other team's 2-yard-line. The team can attempt to kickit over the crossbar and through the goal posts in the manner of a field goal for 1 point (an extra point), or run or pass it into the end zone in the manner of a touchdown for 2 points (a two-point...