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American football

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For other uses, see American football (disambiguation).
Image:Titans Texans.jpg
American football game between the Tennessee Titans and the Houston Texans in 2005
Image:FootballSnap.JPG
American football about to be snapped

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.

Contents

History

Main article: History of American football
Image:Unknown Early American Football Team.jpg
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

Main article: American football rules

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

Field and players

Image:AmFBfield.svg
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

    Image:Football cross.jpg
    A line of scrimmage.
    Image:2006 UT fall scrimmage Snead.JPG
    A quarterback searching for opportunity to throw a pass.
    A running back being tackled when he tries to run with the ball.
    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.)

    Scoring

    Image:Alabama Field-Goal.JPG
    A kicker attempts an extra point.

    A team scores points by the following plays:

    • A touchdown (TD) is worth 6 points. It is scored when a player runs the ball into or catches a pass in his opponent's end zone. A touchdown is analogous to a try in rugby with the major difference being that a try requires the player to place the ball on the ground.
      • After a touchdown, the scoring team attempts a conversion (which is also analogous to the conversion in rugby). The ball is placed at the other team's 3-yard (2.7 m) line (the 2-yard (1.8 m) line in the NFL). The team can attempt to kick it over the crossbar and through the goal posts in the manner of a field goal for 1 point (an extra point or point-after touchdown (PAT)[9]), or run or pass it into the end zone in the manner of a touchdown for 2 points (a two-point conversion). In college football, if the defense intercepts or recovers a fumble during a two point conversion attempt and returns it to the opposing end zone, the defensive team is awarded the two points.
        • A field goal (FG) is worth 3 points, and it is scored by kicking the ball over the crossbar and through the goal posts (uprights). Field goals may be placekicked (kicked when the ball is held vertically against the ground by a teammate) or drop-kicked (extremely uncommon in the modern game, with only two successes in the last 60 years). A field goal is usually attempted on fourth down instead of a punt when the ball is close to the opponent's goal line, or, when there is little or no time left to otherwise score.
        • A safety, worth 2 points, is scored by the defense when a ball-carrier is tackled in his own end zone. Safeties are also awarded if the offense fumbles the ball out-of-bounds in the end zone, has a kick blocked out of the end zone or commits certain penalties in the end zone. Safeties are relatively rare.

        Kickoffs and free kicks

        Each half begins with a kickoff. Teams also kick off after scoring touchdowns and field goals. The ball is kicked using a kicking tee from the team's own 30-yard (27 m) line in the NFL and college football (as of the 2007 season). The other team's kick returner tries to catch the ball and advance it as far as possible. Where he is stopped is the point where the offense will begin its drive, or series of offensive plays. If the kick returner catches the ball in his own end zone, he can either run with the ball, or elect for a touchback by kneeling in the end zone, in which case the receiving team then starts its offensive drive from its own 20 yard line. A touchback also occurs when the kick goes out-of-bounds in the end zone. A kickoff that goes out-of-bounds anywhere other than the end zone before being touched by the receiving team is considered an illegal procedure penalty, and the ball will be placed where it went out of bounds or 30 yards (27 m) from the kickoff spot, depending on which is more advantageous to the opposite team. Unlike with punts, once a kickoff goes 10 yards, it can be recovered by the kicking team. A team, especially one who is losing, can try to take advantage of this by attempting an onside kick. Punts and turnovers in the end zone can also end in a touchback.

        After safeties, the team that gave up the points must free kick the ball to the other team from its own 20 yard line.

        Penalties

        For a complete list of penalties, see American football rules

        Fouls (a type of rule violation) are punished with penalties against the offending team. Most penalties result in moving the football towards the offending team's end zone. If the penalty would move the ball more than half the distance towards the offender's end zone, the penalty becomes half the distance to the goal instead of its normal value.

        Most penalties result in replaying the down. Some defensive penalties give the offense an automatic first down. Conversely, some offensive penalties result in loss of a down (loss of the right to repeat the down). If a penalty gives the offensive team enough yardage to gain a first down, they get a first down, as usual.

        If a foul occurs during a down, an official throws a yellow flag near the spot of the foul. When the down ends, the team that did not commit the foul has the option of accepting the penalty, or declining the penalty and accepting the result of the down.

        A few of the most-common fouls include:

        • False start: An offensive player illegally moves after lining up for--but prior to--the snap. Since the ball is dead, the down is not allowed to begin.
        • Offside: A defensive or offensive player is on the wrong side of the ball when the ball is snapped. This foul occurs simultaneously with the snap.
        • Holding: Illegally grasping or pulling an opponent other than the runner.
        • Pass interference: Illegally contacting an opponent to prevent him from catching a forward pass.
        • Delay of game: Failing to begin a new play after a certain time from the end of the last one.
        • Face mask: Grasping the face mask of another player while attempting to block or tackle him.
        • Illegal block in the back: A blocker contacting a member of the opposing team (who is not the runner) in the back and above the waist.
        • Clipping: A blocker contacting an opponent (who is not the runner) from behind and at or below the waist.

        Under certain circumstances clipping and blocking in the back are legal.

        Variations

        Variations on these basic rules exist, particularly touch and flag football, which are designed as non-contact or limited-contact alternatives to the relative violence of regular American football. In touch and flag football, tackling is not permitted. Offensive players are "tackled" when a defender tags them or removes a flag from their body, respectively. Both of these varieties are played mainly in informal settings such as intramural or youth games. Another variation is "wrap", where a player is "tackled" when another player wraps his arms around the ball carrier. Professional, intercollegiate, and varsity-level high school football invariably use the standard tackling rules.

        Another variation is with the number of players on the field. In sparsely populated areas, it is not uncommon to find high school football teams playing nine-man football, eight-man football or six-man football. Players often play on offense as well as defense. The Arena Football League is a league that plays eight-man football, but also plays indoors and on a much smaller playing surface.

        Players

        Main article: American football positions
        See also: Formation (American football)
        Image:American football positions.svg
        This diagram shows typical offensive and defensive formations. The offense (blue) consists of the quarterback (QB), fullback (FB), tailback (TB), wide receivers (WR), tight end (TE), and offensive linemen (C, OG, OT). The defense (red) consists of the defensive line (DL, DE), linebackers (LBs), cornerbacks (CB), strong safety (SS) and free safety (FS). Because teams can change any or all of the players between plays, the number of players at certain positions may differ on a given play. Here the offense is in the Normal I-Formation while the defense is in a 4-3 Normal.

        Most football players have highly specialized roles. At the college and NFL levels, most play only offense or only defense.

        Offense

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