The Rules of American Football

Each football league adopts its own rules, which cover a wide range of subjects including equipment, uniforms, player eligibility, and behaviour of personnel on the sidelines. The following synopsis covers only the rules governing on-field play of the game, and even so some details may vary from one league to another. Also, this summary covers only the most common situations, and not every contingency that may arise in a game.

Objective

Like most other games of football, the object of American football is to advance the ball towards the opponent's end of the field and score more points than the opposing team within a set time limit.

Field and Players

The American football field is often called the gridiron because the markings on the field resemble that type of grill that can be used to cook food over a fire. The game is played on a rectangular field 120 yards long by 53-1/3 yards wide. The longer boundary lines are sidelines, while the shorter boundary lines are end lines. Near each end of the field is a goal line; they are 100 yards apart. A scoring area called an end zone extends 10 yards beyond each goal line to each end line.

Yard lines cross the field every 5 yards, and are numbered from each goal line to the 50-yard line, or midfield (similar to a typical rugby league field). Two rows of lines, known as hash marks, parallel the side lines near the middle of the field. All plays start with the ball on or between the hash marks.

At the back of each end zone are two goal posts (also called uprights) that are 18.5-feet apart. The posts are connected by a crossbar 10 feet from the ground. Successful kicks must go above the crossbar and between the uprights.

Each team has 11 players on the field at a time. However, teams may substitute for any or all of their players between plays. As a result, players have very specialised roles, and almost all of the 53 players on an NFL team will play in any given game. Thus, teams are divided into three separate units: the offensive team, the defensive team, and the special teams.

Game Duration

A standard football game consists of four 15-minute quarters, with a halftime after the second quarter. However, the clock stops after certain plays, so a game can last more than three hours in real time. If an NFL game is tied after four quarters, the teams play up to another 15 minutes. The first team that scores wins; if neither team scores, the game is a tie. College overtime rules are more complicated.

Advancing the Ball

Advancing the ball in American football resembles the six-tackle rule and the play-the-ball in rugby league football. The team that takes possession of the ball (the offense) has four attempts (called downs) to advance the ball 10-yards towards their opponent's end zone. When the offense gains 10-yards, it gets a first down, or another four downs to gain 10-yards. If the offense fails to gain a first down, it loses possession of th...