American football, referred to as football in the United States and Canada and also known as gridiron,[nb 1] is a team sport played by two teams of eleven players on a rectangular field with goalposts at each end. The offense, which is the team with possession of the oval-shaped football, attempts to advance down the field by running with or passing the ball, while the defense, which is the team without possession of the ball, aims to stop the offense's advance and to take control of the ball for themselves. The offense must advance at least ten yards in four downs, or plays; if they fail, they turn over the football to the defense, but if they succeed, they are given a new set of four downs to continue the drive. Points are primarily scored by advancing the ball into the opposing team's end zone for a touchdown or kicking the ball through the opponent's goalposts for a field goal. The team with the most points at the end of a game wins.
American football evolved in the United States, originating from the sports of soccer and rugby. The first match of American football was played on November 6, 1869 between two college teams, Rutgers and Princeton, under rules based on the rules of soccer at the time. A set of rule changes drawn up from 1880 onward by Walter Camp, the "Father of American Football", established the snap, the line of scrimmage, eleven-player teams, and the concept of downs; later rule changes legalized the forward pass, created the neutral zone, and specified the size and shape of the football. The sport is closely related to Canadian football, which evolved parallel and contemporary to the American game, and most of the features that distinguish American football from rugby and soccer are also present in Canadian football. The two sports are considered the primary variants of gridiron football.
American football as a whole is the most popular sport in the United States. The most popular forms of the game are professional and college football, with the other major levels being high school and youth football. As of 2012, nearly 1.1 million high school athletes and 70,000 college athletes play the sport in the United States annually. The National Football League, the most popular American football league, has the highest average attendance of any professional sports league in the world; its championship game, the Super Bowl, ranks among the most-watched club sporting events in the world, and the league has an annual revenue of around US$10 billion. Other leagues exist worldwide, but the sport does not have the international popularity of other American sports like baseball or basketball.
Etymology and names
In the United States, American football is referred to as "football". The term "football" was officially established in the rulebook for the 1876 college football season, when the sport first shifted from soccer-style rules to rugby-style rules; although it could easily have been called "rugby" at this point, Harvard, one of the primary proponents of the rugby-style game, compromised and did not request the name of the sport be changed to "rugby". The terms "gridiron" or "American football" are favored in English-speaking countries where other codes of football are popular, such as the United Kingdom, Ireland, New Zealand, and Australia.
American football evolved from the sports of soccer and rugby. Rugby, like American football, is a sport where two competing teams vie for control of a ball, which can be kicked through a set of goalposts or run into the opponent's goal area to score points.
What is considered to be the first American football game was played on November 6, 1869, between Rutgers and Princeton, two college teams. The game was played between two teams of 25 players each and used a round ball that could not be picked up or carried. It could, however, be kicked or batted with the feet, hands, head or sides, with the ultimate goal being to advance it into the opponent's goal. Rutgers won the game 6 goals to 4.Collegiate play continued for several years in which matches were played using the rules of the host school. Representatives of Yale, Columbia, Princeton and Rutgers met on October 19, 1873 to create a standard set of rules for all schools to adhere to. Teams were set at 20 players each, and fields of 400 by 250 feet (122 m × 76 m) were specified. Harvard abstained from the conference, as they favored a rugby-style game that allowed running with the ball.After playing McGill University using both Canadian and American rules, the Harvard players preferred the Canadian style having only 11 men on the field, running the ball without having to be chased by an opponent, the forward pass, tackling, and using an oblong instead of a round ball.
An 1875 Harvard–Yale game played under rugby-style rules was observed by two impressed Princeton athletes. These players introduced the sport to Princeton, a feat the Professional Football Researchers Association compared to "selling refrigerators to Eskimos." Princeton, Harvard, Yale and Columbia then agreed to intercollegiate play using a form of rugby union rules with a modified scoring system. These schools formed the Intercollegiate Football Association, although Yale did not join until 1879. Yale player Walter Camp, now regarded as the "Father of American Football", secured rule changes in 1880 that reduced the size of each team from 15 to 11 players and instituted the snap to replace the chaotic and inconsistent scrum.
Evolution of the game
The introduction of the snap resulted in unexpected consequences. Prior to the snap, the strategy had been to punt if a scrum resulted in bad field position. However, a group of Princeton players realized that, as the snap was uncontested, they now could hold the ball indefinitely to prevent their opponent from scoring. In 1881, both teams in a game between Yale and Princeton used this strategy to maintain their undefeated records. Each team held the ball, gaining no ground, for an entire half, resulting in a 0–0 tie. This "block game" proved extremely unpopular with the spectators and fans of both teams.
A rule change was necessary to prevent this strategy from taking hold, and a reversion to the scrum was considered. However, Camp successfully proposed a rule in 1882 that limited each team to three downs, or tackles, to advance the ball five yards. Failure to advance the ball the required distance within those three downs would result in control of the ball being forfeited to the other team. This change effectively made American football a separate sport from rugby, and the resulting five-yard lines added to the field to measure distances made it resemble a gridiron in appearance. Other major rule changes included a reduction of the field size to 110 by 53 1⁄3 yards (100.6 m × 48.8 m) and the adoption of a scoring system that awarded four points for a touchdown, two for a safety and a goal following a touchdown, and five for a goal from field. Additionally, tackling below the waist was legalized, and a static line of scrimmage was instituted.
Despite these new rules, football remained a violent sport. Dangerous mass-formations like the flying wedge resulted in serious injuries and deaths. A 1905 peak of 19 fatalities nationwide resulted in a threat by President Theodore Roosevelt to abolish the game unless major changes were made. In response, 62 colleges and universities met in New York City to discuss rule changes on December 28, 1905, and these proceedings resulted in the formation of the Intercollegiate Athletic Association of the United States, later renamed the National Collegiate Athletic Association (NCAA).
The legal forward pass was introduced in 1906, although its impact was initially minimal due to the restrictions placed on its use. Other rule changes introduced that year included the reduction of the time of play from 70 to 60 minutes and the increase of the distance required for a first down from 5 to 10 yards (4.6 to 9.1 m). To reduce infighting and dirty play between teams, the neutral zone was created along the width of the football prior to the snap. Scoring was also adjusted: field goals were lowered to three points in 1909 and touchdowns were raised to six points in 1912. The field was also reduced to 100 yards (91 m) long, but two 10-yard-long (9.1 m) end zones were created, and teams were given four downs instead of three to advance the ball 10 yards (9.1 m). The roughing the passer penalty was implemented in 1914, and eligible players were first allowed to catch the ball anywhere on the field in 1918.
On November 12, 1892, William "Pudge" Heffelfinger was paid $500 to play a game for the Allegheny Athletic Association in a match against the Pittsburgh Athletic Club. This is the first recorded instance of a player being paid to participate in a game of American football, although many athletic clubs in the 1880s offered indirect benefits, such as helping players attain employment, giving out trophies or watches that players could pawn for money, or paying double in expense money. Despite these extra benefits, the game had a strict sense of amateurism at the time, and direct payment to players was frowned upon, if not outright prohibited.
Over time, professional play became increasingly common, and with it came rising salaries and unpredictable player movement, as well as the illegal payment of college players who were still in school. The National Football League (NFL), a group of professional teams that was originally established in 1920 as the American Professional Football Association, aimed to solve these problems. This new league's stated goals included an end to bidding wars over players, prevention of the use of college players, and abolition of the practice of paying players to leave another team. By 1922, the NFL had established itself as the premier professional football league.
The dominant form of football at the time was played at the collegiate level, but the upstart NFL received a boost to its legitimacy in 1925 when an NFL team, the Pottsville Maroons, defeated a team of Notre Dame all-stars in an exhibition game.A greater emphasis on the passing game helped professional football to further distinguish itself from the college game during the late 1930s. Football in general became increasingly popular following the 1958 NFL Championship game, a match between the Baltimore Colts and the New York Giants that is still referred to as the "Greatest Game Ever Played". The game, a 23–17 overtime victory by the Colts, was seen by millions of television viewers and had a major impact on the popularity of the sport. This, along with the innovations introduced by the new American Football League (AFL) in the early 1960s, helped football to become the most popular sport in the United States by the mid-1960s.
The rival AFL arose in 1960 and challenged the NFL's dominance. The AFL began in relative obscurity but eventually thrived, with an initial television contract with the ABC network. The AFL's existence forced the conservative NFL to expand to Dallas and Minnesota in an attempt to destroy the new league. Meanwhile, the AFL introduced many new features to Professional Football in the United States: official time on the scoreboard clock, rather than on a watch in the referee's pocket, as the NFL did; optional two-point conversions by pass or run after touchdowns; names on the jerseys of players; and several others, including expansion of the role of minority players, actively recruited by the league in contrast to the NFL. The AFL also signed several star college players that had also been drafted by NFL teams. Competition for players heated up in 1965, when the AFL New York Jets signed rookie Joe Namath to a then-record $437,000 contract (equivalent to $2.71 million in 2018). A five-year, $40 million (equivalent to $2.48 billion in 2018) NBC television contract followed, which helped to sustain the young league. The bidding war for players ended in 1966, when NFL owners approached the AFL regarding a merger, and the two leagues agreed on one that would take full effect in 1970. This agreement provided for a common draft that would take place each year, and it instituted an annual World Championship game to be played between the champions of each league. That game began play at the end of the 1966 season. Once the merger was completed, it was no longer a championship game between two leagues, and reverted to the NFL championship game, which came to be known as the Super Bowl.
College football maintained a tradition of postseason bowl games. Each bowl game would be associated with a particular conference, and earning a spot in a bowl game was the reward for winning a conference. This arrangement was profitable, but it tended to prevent the two top-ranked teams from meeting in a true national championship game, as they would normally be committed to the bowl games of their respective conferences. Several systems have been used since 1992 to determine a national champion of college football. The first was the Bowl Coalition, in place from 1992 to 1994. This was replaced in 1995 by the Bowl Alliance, which gave way in 1997 to the Bowl Championship Series (BCS). The BCS arrangement proved to be controversial, and was replaced in 2014 by the College Football Playoff (CFP).
Teams and positions
A football game is played between two teams of 11 players each Playing with more on the field is punishable by a penalty.Teams may substitute any number of their players between downs; this "platoon" system replaced the original system, which featured limited substitution rules, and has resulted in teams utilizing specialized offensive, defensive and special teams squads.
Individual players in a football game must be designated with a uniform number between 1 and 99. NFL teams are required to number their players by a league-approved numbering system, and any exceptions must be approved by the Commissioner. NCAA and NFHS teams are "strongly advised" to number their offensive players according to a league-suggested numbering scheme.
Although the sport is played almost exclusively by men, women are eligible to play in high school, college, and professional football. No woman has ever played in the NFL, but women have played in high school and college football games. In 2018, 1,100 of the 225,000 players in Pop Warner Little Scholars youth football were girls, and around 11% of the 5.5 million Americans who report playing tackle football are female according to the Sports and Fitness Industry Association. Women can also serve as officials; Sarah Thomas became the NFL’s first female official in 2015.
The offensive team must line up in a legal formation before they can snap the ball. An offensive formation is considered illegal if there are more than four players in the backfield or fewer than five players numbered 50–79 on the offensive line. Players can temporarily line up in a position whose eligibility is different from what their number permits as long as they immediately report the change to the referee, who then informs the defensive team of the change. Neither team's players, with the exception of the snapper, are allowed to line up in or cross the neutral zone until the ball is snapped. Interior offensive linemen are not allowed to move until the snap of the ball.
The main backfield positions are the quarterback (QB), halfback/tailback (HB/TB) and fullback (FB). The quarterback is the leader of the offense. Either the quarterback or a coach calls the plays. Quarterbacks typically inform the rest of the offense of the play in the huddle before the team lines up. The quarterback lines up behind the center to take the snap and then hands the ball off, throws it or runs with it.
The primary role of the halfback, also known as the running back or tailback, is to carry the ball on running plays. Halfbacks may also serve as receivers. Fullbacks tend to be larger than halfbacks and function primarily as blockers, but they are sometimes used as runners in short-yardage situations and are seldom used in passing situations.
The offensive line (OL) consists of several players whose primary function is to block members of the defensive line from tackling the ball carrier on running plays or sacking the quarterback on passing plays. The leader of the offensive line is the center (C), who is responsible for snapping the ball to the quarterback, blocking, and for making sure that the other linemen do their jobs during the play.On either side of the center are the guards (G), while tackles (T) line up outside the guards.
The principal receivers are the wide receivers (WR) and the tight ends (TE). Wide receivers line up on or near the line of scrimmage, split outside the line. The main goal of the wide receiver is to catch passes thrown by the quarterback, but they may also function as decoys or as blockers during running plays. Tight ends line up outside the tackles and function both as receivers and as blockers.
The role of the defense is to prevent the offense from scoring by tackling the ball carrier or by forcing turnovers (interceptions or fumbles).
The defensive line (DL) consists of defensive ends (DE) and defensive tackles (DT). Defensive ends line up on the ends of the line, while defensive tackles line up inside, between the defensive ends. The primary responsibilities of defensive ends and defensive tackles is to stop running plays on the outside and inside, respectively, to pressure the quarterback on passing plays, and to occupy the line so that the linebackers can break through.
Linebackers line up behind the defensive line but in front of the defensive backfield. They are divided into two types: middle linebackers (MLB) and outside linebackers (OLB). Linebackers are the defensive leaders and call the defensive plays. Their diverse roles include defending the run, pressuring the quarterback, and guarding backs, wide receivers and tight ends in the passing game.
The defensive backfield, often called the secondary, consists of cornerbacks (CB) and safeties (S). Safeties are themselves divided into free safeties (FS) and strong safeties (SS). Cornerbacks line up outside the defensive formation, typically opposite of a receiver so as to be able to cover him, while safeties line up between the cornerbacks but farther back in the secondary. Safeties are the last line of defense, and are responsible for stopping deep passing plays as well as running plays.
Special teams unit
The special teams unit is responsible for all kicking plays. The special teams unit of the team in control of the ball will try to execute field goal (FG) attempts, punts and kickoffs, while the opposing team's unit will aim to block or return them.
Three positions are specific to the field goal and PAT (point-after-touchdown) unit: the placekicker (K or PK), holder (H) and long snapper (LS). The long snapper's job is to snap the football to the holder, who will catch and position it for the placekicker. There is not usually a holder on kickoffs, because the ball is kicked off of a tee; however, a holder may be used in certain situations, such as if wind is preventing the ball from remaining upright on the tee. The player on the receiving team who catches the ball is known as the kickoff returner (KR).
The positions specific to punt plays are the punter (P), long snapper, upback and gunner. The long snapper snaps the football directly to the punter, who then drops and kicks it before it hits the ground. Gunners line up split outside the line and race down the field, aiming to tackle the punt returner (PR) – the player that catches the punt. Upbacks line up a short distance behind the line of scrimmage, providing additional protection to the punter.
n football, the winner is the team that has scored more points at the end of the game. There are multiple ways to score in a football game. The touchdown (TD), worth six points, is the most valuable scoring play in American football. A touchdown is scored when a live ball is advanced into, caught in, or recovered in the end zone of the opposing team. The scoring team then attempts a try or conversion, more commonly known as the point(s)-after-touchdown (PAT), which is a single scoring opportunity. A PAT is most commonly attempted from the two- or three-yard line, depending on the level of play. If scored by a placekick or dropkick through the goal posts, it is worth one point, typically called the extra point, and if scored by what would normally be a touchdown it is worth two points, typically called the two-point conversion. In general, the extra point is almost always successful while the two-point conversion is a much riskier play with a higher probability of failure; accordingly, extra point attempts are far more common than two-point conversion attempts.
A field goal (FG), worth three points, is scored when the ball is placekicked or dropkicked through the uprights and over the crossbars of the defense's goalposts. After a PAT attempt or successful field goal, the scoring team must kick the ball off to the other team.
A safety is scored when the ball carrier is tackled in their own end zone. Safeties are worth two points, which are awarded to the defense. In addition, the team that conceded the safety must kick the ball to the scoring team via a free kick.
Field and equipment
Football games are played on a rectangular field that measures 120 yards (110 m) long and 53 1⁄3 yards (48.8 m) wide. Lines marked along the ends and sides of the field are known respectively as the end lines and sidelines, and goal lines are marked 10 yards (9.1 m) inward from each end line.
Weighted pylons are placed on the inside corner of the intersections of the goal lines and end lines. White markings on the field identify the distance from the end zone. Inbound lines, or hash marks, are short parallel lines that mark off 1-yard (0.91 m) increments. Yard lines, which can run the width of the field, are marked every 5 yards (4.6 m). A one-yard-wide line is placed at each end of the field; this line is marked at the center of the two-yard line in professional play and at the three-yard line in college play. Numerals that display the distance from the closest goal line in yards are placed on both sides of the field every ten yards.
Goalposts are located at the center of the plane of each of the two end lines. The crossbar of these posts is 10 feet (3.0 m) above the ground, with vertical uprights at the end of the crossbar 18 feet 6 inches (5.64 m) apart for professional and collegiate play and 23 feet 4 inches (7.11 m) apart for high school play. The uprights extend vertically 35 feet (11 m) on professional fields, a minimum of 10 yards (9.1 m) on college fields, and a minimum of 10 feet (3.0 m) on high school fields. Goal posts are padded at the base, and orange ribbons are normally placed at the tip of each upright.
The football itself is an oval ball, similar to the balls used in rugby or Australian rules football. At all levels of play, the football is inflated to 12 1⁄2 to 13 1⁄2 pounds per square inch (86 to 93 kPa) and weighs 14 to 15 ounces (400 to 430 g); beyond that, the exact dimensions vary slightly. In professional play the ball has a long axis of 11 to 11 1⁄4 inches (28 to 29 cm), a long circumference of 28 to 28 1⁄2 inches (71 to 72 cm), and a short circumference of 21 to 21 1⁄4 inches (53 to 54 cm), while in college and high school play the ball has a long axis of 10 7⁄8 to 11 7⁄16 inches (27.6 to 29.1 cm), a long circumference of 27 3⁄4 to 28 1⁄2 inches (70 to 72 cm), and a short circumference of 20 3⁄4 to 21 1⁄4 inches (53 to 54 cm).
Duration and time stoppages
Football games last for a total of 60 minutes in professional and college play and are divided into two halves of 30 minutes and four quarters of 15 minutes. High school football games are 48 minutes in length with two halves of 24 minutes and four quarters of 12 minutes. The two halves are separated by a halftime period, and the first and third quarters are also followed by a short break. Prior to the start of the game, the referee and team captains for each team meet at midfield for a coin toss. The visiting team is allowed to call "heads" or "tails"; the winner of the toss is allowed to decide between choosing whether to receive or kick off the ball or choosing which goal they want to defend, but they can also defer their choice until the second half. The losing team, unless the winning team decides to defer, is allowed to choose the option the winning team did not select, and receives the option to receive, kick, or select a goal to defend to begin the second half. Most teams choose to receive or defer, because choosing to kick the ball to start the game would allow the other team to choose which goal to defend. Teams switch goals following the first and third quarters. If a down is in progress when a quarter ends, play continues until the down is completed.
Games last longer than their defined length due to play stoppages—the average NFL game lasts slightly over three hours. Time in a football game is measured by the game clock. An operator is responsible for starting, stopping and operating the game clock based on the direction of the appropriate official. A separate clock, the play clock, is used to determine if a delay of game infraction has been committed. If the play clock expires before the ball has been snapped or free-kicked, a delay of game foul is called on the offense. The play clock is set to 40 seconds in professional and college football and to 25 seconds in high school play or following certain administrative stoppages in the former levels of play
Advancing the ball and downs
There are two main ways that the offense can advance the ball: running and passing. In a typical play, the center passes the ball backwards and under their legs to the quarterback in a process known as the snap. The quarterback then either hands the ball off to a back, throws the ball, or runs with it. The play ends when the player with the ball is tackled or goes out of bounds or a pass hits the ground without a player having caught it. A forward pass can only be legally attempted if the passer is behind the line of scrimmage, and only one forward pass can be attempted per down. Like in rugby, players can also pass the ball backwards at any point during a play. In the NFL, a down also ends immediately if the runner's helmet comes off.
The offense is given a series of four plays, known as downs. If the offense advances ten or more yards in the four downs, they are awarded a new set of four downs. If they fail to advance ten yards, possession of the football is turned over to the defense. In most situations, if the offense reaches their fourth down they will punt the ball to the other team, which forces them to begin their drive from further down the field; if they are in field goal range, they might instead attempt to score a field goal. A group of officials, the chain crew, keeps track of both the downs and the distance measurements. On television, a yellow line is electronically superimposed on the field to show the first down line to the viewing audience.
There are two categories of kicks in football: scrimmage kicks, which can be executed by the offensive team on any down from behind or on the line of scrimmage, and free kicks.The free kicks are the kickoff, which starts the first and third quarters and overtime and follows a try attempt or a successful field goal, and the safety kick, which follows a safety.
On a kickoff, the ball is placed at the 35-yard line of the kicking team in professional and college play and at the 40-yard line in high school play. The ball may be drop-kicked or place-kicked. If a place kick is chosen, the ball can be placed on the ground or on a tee, and a holder may be used in either case. On a safety kick, the kicking team kicks the ball from their own 20-yard line. They can punt, drop-kick or place-kick the ball, but a tee may not be used in professional play. Any member of the receiving team may catch or advance the ball, and the ball may be recovered by the kicking team once it has gone at least ten yards and has touched the ground or has been touched by any member of the receiving team.
The three types of scrimmage kicks are place kicks, drop kicks, and punts. Only place kicks and drop kicks can score points. The place kick is the standard method used to score points, because the pointy shape of the football makes it difficult to reliably drop kick. Once the ball has been kicked from a scrimmage kick, it can be advanced by the kicking team only if it is caught or recovered behind the line of scrimmage. If it is touched or recovered by the kicking team beyond this line, it becomes dead at the spot where it was touched. The kicking team is prohibited from interfering with the receiver's opportunity to catch the ball, and the receiving team has the option of signaling for a fair catch. This prohibits the defense from blocking into or tackling the receiver, but the play ends as soon as the ball is caught and the ball may not be advanced. (see more https://en.wikipedia.org/wiki/American_football)Source : https://en.wikipedia.org/wiki/American_football