American football

American football, known in the United States simply as football,^[1] is a competitive team sport known for mixing strategy with intense physical play. The object of the game is to score points by advancing the ball^[2] into the opposing team's end zone. The ball can be advanced by carrying it (a running play) or by throwing it to a teammate (a passing play). Points can be scored in a variety of ways , including carrying the ball over the goal line, catching a pass from beyond the goal line, tackling an opposing ball carrier in his own end zone, or kicking the ball through the goal posts on the opposing side. The winner is the team with the most points when time expires at the end of the last play.

American football is known for having only a small following outside the United States, despite attempts by the National Football League (NFL) to globalize the game.

History

An early American football team, from the turn of the twentieth century

The history of American football can be traced to early versions of rugby football. Both games have their origin in varieties of football played in the United Kingdom in the mid-19th century, in which a ball is kicked at a goal and/or run over a line.

American football resulted from several major divergences from rugby football, most notably the rule changes instituted by Walter Camp, considered the "Father of American Football". Among these important changes were the introduction of the line of scrimmage and of down-and-distance rules. In the late 19th and early 20th centuries, gameplay developments by college coaches such as Amos Alonzo Stagg, Knute Rockne, and Glenn "Pop" Warner helped take advantage of the newly introduced forward pass. The popularity of collegiate football grew as it became the dominant version of the sport for the first half of the twentieth century. Bowl games, a college football tradition, attracted a national audience for collegiate teams. Bolstered by fierce rivalries, college football still holds widespread appeal in the US.^[3][4][5]

The origin of professional football can be traced back to 1892, with William "Pudge" Heffelfinger's $500 contract to play in a game for the Allegheny Athletic Association against the Pittsburgh Athletic Club. In 1920 the American Professional Football Association was formed. This league changed its name to the National Football League (NFL) two years later, and eventually became the major league of American football. Primarily a sport of Midwestern, industrial towns in the United States, professional football eventually became a national phenomenon. Football's increasing popularity is usually traced to the 1958 NFL Championship Game, a contest that has been dubbed the "Greatest Game Ever Played". A rival league to the NFL, the American Football League (AFL), began play in 1960; the pressure it put on the senior league led to a merger between the two leagues and the creation of the Super Bowl, which has become the most watched television event in the United States on an annual basis. ^[6]

Rules

The object of American football is to score more points than the opposing team within the time limit.

Field and players

The numbers on the field indicate the number of yards to the nearest end zone.

American football is played on a field 360 feet (120 yards/109.7 m) long by 160 feet (53.3 yards/48.8 m) 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 (91.4 m) apart. A scoring area called an end zone extends 10 yards (9.1 m) beyond each goal line to each end line.

Yard lines cross the field every 5 yards (4.6 m), and are numbered every 10 yards from each goal line to the 50-yard line, or midfield (similar to a typical rugby league field). Two rows of lines, known as inbounds lines or hash marks, parallel the sidelines 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 goalposts (also called uprights) that are 18.5 feet (5.6 m) apart (24 feet (7.3 m) in high school). The posts are connected by a crossbar 10 feet (305 cm) from the ground.

Each team has 11 players on the field at a time. However, teams may substitute for any or all of their players, if time allows, during the break between plays. As a result, players have very specialized roles, and, sometimes (although rarely) almost all of the (at least) 46 active players on an NFL team will play in any given game. Thus, teams are divided into three separate units: the offense, the defense and the special teams.

Start of halves

Similar to association football, the game begins with a coin toss to determine who will kick off to begin the games and which goal each team will defend. The options will be presented again to start the second half; the choices for the first half do not automatically determine the start of the second half. The referee will conduct the coin toss with the captains (or sometimes coaches) of the opposing teams. The team that wins the coin toss has three options:

1. They may choose to either receive the opening kickoff or to kick off
2. They may choose which goal to defend
3. They may choose to defer the first choice to the other team and have first choice to start the second half (except in the NFL)^[7]

Whatever the first team chooses, the second team has the option on the other choice (for example, if the first team elects to receive at the start of the game, the second team can decide which goal to defend).

At the start of the second half, the options to kick, receive, or choose a goal to defend are presented to the captains again. The team which did not choose first to start the first half (or which deferred its privilege to choose first) now gets first choice of options.^[8]

Game duration

A standard football game consists of four 15-minute (typically 12 minutes in high-school football) quarters, with a half-time intermission after the second quarter. The clock stops after certain plays; therefore, a game can last considerably longer (often more than three hours in real time), and if a game is broadcast on television, TV timeouts are taken at certain intervals of the game to broadcast commercials outside of game action. If an NFL game is tied after four quarters, the teams play an additional period lasting up to 15 minutes. In an NFL overtime game, the first team that scores wins, even if the other team does not get a possession; this is referred to as sudden death. In a regular-season NFL game, if neither team scores in overtime, the game is a tie. In an NFL playoff game, additional overtime periods are played, as needed, to determine a winner. College overtime rules are more complicated and are described in Overtime (sport).

Advancing the ball

A line of scrimmage.

A quarterback searching for opportunity to throw a pass.

A running back being tackled when he tries to run with the ball.

Advancing the ball in American football resembles the six-tackle rule and the play-the-ball in rugby league. The team that takes possession of the ball (the offense) has four attempts, called downs, to advance the ball 10 yards (9.1 m) towards their opponent's (the defense's) end zone. When the offense gains 10 yards, it gets a first down, which means the team has another set of four downs to gain yet another 10 yards or score with. If the offense fails to gain a first down (10 yards) after 4 downs, the other team gets possession of the ball at the spot of the football, beginning with their first down.

Except at the beginning of halves and after scores, the ball is always put into play by a snap. Offensive players line up facing defensive players at the line of scrimmage (the position on the field where the play begins). One offensive player, the center, then passes (or "snaps") the ball between his legs to a teammate, usually the quarterback.

Players can then advance the ball in two ways:

1. By running with the ball, also known as rushing. One ball-carrier can hand the ball to another player or throw backwards to another player. These are known as a handoff and a backward pass (sometimes referred to as a lateral) respectively.
2. By throwing the ball to a teammate, known as a forward pass or as passing the football. The forward pass is a key factor distinguishing American and Canadian football from other football sports. The offense can throw the ball forward only once during a down and only from behind the line of scrimmage. The ball can be thrown, pitched, handed-off, or tossed sideways or backwards at any time.

A down ends, and the ball becomes dead, after any of the following:

• The player with the ball is forced to the ground (tackled) or has his forward progress halted by members of the other team (as determined by an official).
• A forward pass flies beyond the dimensions of the field (out of bounds) or touches the ground before it is caught. This is known as an incomplete pass. The ball is returned to the most recent line of scrimmage for the next down.
• The ball or the player with the ball goes out of bounds.
• A team scores.

Officials blow a whistle to notify players that the down is over.

Before each down, each team chooses a play, or coordinated movements and actions, that the players should follow on a down. Sometimes, downs themselves are referred to as "plays."

Change of possession

The offense maintains possession of the ball unless one of the following things occurs:

• The team fails to get a first down— i.e., in four downs they fail to move the ball past a line 10 yards ahead of where they got their last first down (it is possible to be downed behind the current line of scrimmage, "losing yardage"). The defensive team takes over the ball at the spot where the 4th-down play ends. A change of possession in this manner is commonly called a turnover on downs, but is not credited as a defensive "turnover" in official statistics. Instead, it goes against the offense's 4th down efficiency percentage.
• The offense scores a touchdown or field goal. The team that scored then kicks the ball to the other team in a special play called a kickoff.
• The offense punts the ball to the defense. A punt is a kick in which a player drops the ball and kicks it before it hits the ground. Punts are nearly always made on fourth down (though see quick kick), when the offensive team does not want to risk giving up the ball to the other team at its current spot on the field (through a failed attempt to make a first down) and feels it is too far from the other team's goal posts to attempt a field goal.
• A defensive player catches a forward pass. This is called an interception, and the player who makes the interception can run with the ball until he is tackled, forced out of bounds, or scores.
• An offensive player drops the ball (a fumble) and a defensive player picks it up. As with interceptions, a player recovering a fumble can run with the ball until tackled or forced out of bounds. Backward passes that are not caught do not cause the down to end like incomplete forward passes do; instead the ball is still live as if it had been fumbled. Lost fumbles and interceptions are together known as turnovers
• The offensive team misses a field goal attempt. The defensive team gets the ball at the spot where the previous play began (or, in the NFL, at the spot of the kick). If the unsuccessful kick was attempted from within 20 yards (18.3 m) of the end zone, the other team gets the ball at its own 20 yard line (that is, 20 yards from the end zone). If a field goal is missed and the ball remains in the field of play, a defensive player may also catch the ball and attempt to advance it.
• In his own end zone, an offensive ballcarrier is tackled, forced out of bounds or loses the ball out of bounds, or the offense commits certain penalties. This fairly rare occurrence is called a safety.
• An offensive ballcarrier fumbles the ball forward into the end zone, and then the ball goes out of bounds. This extremely rare occurrence leads to a touchback, with the ball going over to the opposing team at their 20 yard line. (Note that touchbacks during non-offensive special teams plays, such as punts and kickoffs, are quite common.)