Football is a contact sport played between two teams on a field 160 feet wide and 360 feet long. The purpose of the game is to score points by advancing a ball beyond a goal line into an area (the end zone) at the end of the opposing team’s side. Each football team is allowed 11 players on the field. The team that scores the most points wins the game. In American Football, the ball may be advanced by running with it or throwing it to a team member. The goal lines of the opposing teams are 300 feet (100 yards) apart. Professional American Football teams together constitute the National Football League, the highest level American Football organization.
At each end of the field there are goal posts used to score field goals. The vertical posts are 18 feet, six inches apart for professional and college football, and 23 feet, 4 inches apart for high school football. The horizontal bar between the posts is 10 feet high.
The field is marked between the goal lines by hash marks in 1-yard increments. Every ten yards, the number of yards from the nearest goal line is marked in large numbers. The 50-yard line marks the middle of the field.
Each team can score points by a player carrying the ball beyond the opposing team’s goal line, by catching a ball thrown over the goal line, kicking a ball between the uprights and over the crossbar of the opponent’s goal posts, or tackling and bringing down an opponent player carrying the ball in the opponent’s end zone.
The rules for professional, college, and high school football vary somewhat, but are consistent in most respects. The total duration of a game can vary significantly (it is usually about three hours), but the play time, that is, the time during which the ball may be moved and points may be scored, is 60 minutes in professional and college football. The 60 minutes are divided into four quarters of 15 minutes each. High school football customarily uses 12 minute quarters. After the second quarter is completed, an intercalary period of no play, halftime, is observed. Halftime duration is 12 minutes for professional football and 20 minutes for college football.
The referee controls the game clock and stops the clock as necessary to facilitate the conduct of the game. For example, after an incomplete pass or any play that ends out of bounds. In addition, each team is allowed three timeouts in each half that they may use at their own discretion.
For National Football League games, if at the end of the normal four quarters the score is a tie, an extra period is played. This tiebreaker period has a maximum duration of 15 minutes. The team that first scores any points wins the game. If at the end of the extra period neither team has scored, the game results in a tie.
The Coin Toss
Before the start of play, the referee tosses a coin with representatives (usually the captains) of the two teams. The team that wins the coin toss has three options: they may choose whether to kick or receive the opening kickoff, which goal to defend, or to let the other team make the first choice. The team that loses the coin toss gets to make the other choice (if the team winning the coin toss chose to kick, then the other team picks which goal to defend). The team that does not make the first choice in the first half gets to make the first choice in the second half.
Play begins with a kickoff. Kickoffs also occur at the start of the second half and after scoring touchdowns and field goals. The kicker kicks the ball toward the opposing team’s goal line from a kicking tee placed at his team’s 35 yard line (in professional football) or 30-yard line (in college football). The opposing team’s kick returner attempts to catch the ball and carry it forward as far as possible.
Unless the player catching the kicked ball succeeds in reaching the opposing team’s goal line and scoring a touchdown (a rare occurrence) the offense begins its drive from the point where he is stopped. If the kick returner catches the ball in his own end zone, he can either run with the ball, or elect to perform a touchback by kneeling in the end zone. If a touchback is elected, the team receiving the kick begins its offensive drive from its own 20 yard line.
A kickoff results in a foul if the ball goes out of bounds other than at the end zone before being touched by the receiving team. If this happens the ball is placed at the yard line where it went out of bounds, or 30 yards from the kickoff position, whichever is more advantageous to the receiving team.
American Football uses a leather ball (the football) shaped to facilitate its being thrown. The shape is like a prolate spheroid with pointy ends, 11 inches long and 22 inches in circumference. The football has a polyurethane or rubber internal lining, is inflated to a pressure of 12.5 to 13.5 psi, and weighs 14 to 15 ounces. At the start of a down, the ball is in the possession of the center, a player of the offense usually positioned in the middle of the offensive line.
The team having possession of the football carries out the offense against the opposing team. The offense is allowed four attempts in which to move the ball at least ten yards toward the opponent’s end zone. Each attempt is called a down. If the first attempt fails to advance the ball ten yards or more, but the offense has not lost possession of the ball, the offense gets a second opportunity. The second down starts at the position where the first down ended. The third and fourth downs are played similarly. If during the allowed four downs the offense succeeds in advancing the ball at least ten yards, it is awarded a new first down and begins a new sequence of four downs in which to possibly advance another ten yards.
The offense may lose control of the ball through interception of a pass attempt or through one of its players being tackled while carrying the ball. If a player is tackled, falls on the ball, and loses his grip on the ball as he hits the ground, the ball is considered dead when he lands. While the ball is dead, no team may attempt to advance it, and no change of possession can take place. If an offensive player is by himself, has not been tackled, and then slips or otherwise loses his grip on the ball when he falls to the ground, the player is considered to have fumbled the ball, which may then be grabbed by any player.
By advancing the ball closer to the opposing team’s goal line the offense becomes more likely to score a touchdown by carrying the ball into the end zone or catching a ball thrown over the goal line. The status of an offensive drive is stated in terms of the relative progress toward the desired ten yard gain. Thus, a first down starting status where the Rhinos team has possession of the ball at their 30-yard line is described as “first down and 10, Rhinos 30-yard line.” If during first down play the ball is advanced 5 yards and the offense retains possession, the status at the start of the second down is described as “second down and 5, Rhinos 35-yard line.” If during second down play the ball is advanced 7 yards, the Rhinos (having advanced a total of 12 yards) are awarded a new first down. The new situation is described as “first down and 10, Rhinos 42-yard line.”
If after the fourth down the offense has not succeeded in advancing the ball at least ten yards, the opposing team gains possession of the ball at the position where the fourth down ended. If at any time during the offense’s drive the opposing team gains control of the ball, the team that was previously the defense switches to the offense role, starting at the position where it gained control of the ball. Play resumes with the team that was previously the defense now carrying out the offense and attempting to advance the ball in the opposite direction.
Both teams, whether they are playing offense or defense, have practiced a variety of plays, and can choose an appropriate play that best fits the current situation. The scripts for these plays, denoting planned action sequences for the players, are documented in a playbook. Before the start of each down, the quarterback informs his team members of the specific play sequence to be attempted, using a predetermined code. The players assumed prearranged positions and execute the planned tactics as best they can. The defense also has recourse its own playbook with a set of responses to anticipated offensive plays, and prior to the start of play chooses a defensive tactic appropriate to the situation.
The offense is the team which has possession of the ball. It is their job to advance the ball towards the opponent’s end zone to score points. The two main offensive moves are rushing and passing. Field goals, punts, and extra point attempts can also be selected. Some plays that are considered safe are also likely to gain only a few yards. Other plays can result in very significant gains, but are considered risky because of a chance of losing control of the ball or failing to execute as planned.
In rushing, a player of the offense typically runs with the ball toward the opponent’s end zone and his teammates attempt to keep defensive players from impeding his progress.
In passing plays, typically the quarterback throws the football to an offense player that has positioned himself closer to the opponent’s end zone. If the intended player catches the ball, he runs toward the opponent’s end zone while his teammates try to protect him from defensive players trying to stop him. In a passing play, the defense will try to intercept the thrown ball before an offensive player can catch it.
Any player carrying the ball may execute a lateral pass, thrown sideways or backwards with respect to the opposition’s end zone. A lateral pass does not advance the football, but it may be executed by any player from anywhere on the field. Such a pass may have a disconcerting effect on the opposition and may be part of a trick play.
The offense may decide to attempt a field goal in circumstances (usually fourth down) when it is too far from the opponent’s end zone to expect to complete a touchdown, or when the team is close to running out of time. In a field goal, an assisting player typically holds the football vertically on the field and then the kicking player kicks the ball. If the ball travels between the uprights and over the crossbar of the goal posts in the opponent’s end zone the field goal is successful and the team scores three points. The kicker has the option (seldom exercised) of drop kicking the ball instead of kicking a ball held on the ground by a teammate.
If the kick is short, the defensive team’s kick returner attempts to catch the kicked ball and advance with it toward the opponent’s end zone as far as possible. The team newly in possession begins its offensive drive at the position where the kick returner is stopped.
Sometimes the team carrying out the offense encounters a situation (often on fourth down) such that it risks losing the ball to the defense near its current position on the field through a failed passing or running play while also being too far from the opponent’s end zone to make a field goal. The offense may then decide to punt the ball. In a punt, a player drops the ball and kicks it toward the players on the defense before it hits the ground. The opposing team gains control of the ball, but at a position closer to its own end zone.
The kick returner attempts to catch the kicked ball and take it toward the opponent’s end zone. The team gaining possession begins its offensive drive at the position where the kick returner is stopped.
The principal objective of the offensive drive is to score a touchdown, which is worth six points. In a touchdown a player takes the football into the opponent team’s end zone, or catches a pass in the opponent’s end zone. To score a touchdown, the scoring player must have possession of the ball while any part of the ball is within the opponent’s end zone, that is, beyond a vertical plane rising from the leading edge of the opponent’s goal line strip.
When a team scores a touchdown, it has the opportunity to score extra points before it yields control of the ball to the other team. The football is placed at the opponent’s 3-yard line, or at the 2-yard line in the National Football League, and the team chooses to either kick (as in a field goal), or attempt a pass or run into the end zone. The offense gains one extra point if a kick is successful, or two points (a conversion) if a player takes the football into the opponent team’s end zone, or catches a pass in the opponent’s end zone (as in a touchdown).
A safety is relatively rare, a kind of negative consequence. It occurs when the team in possession at the end of a down is responsible for the ball becoming dead behind its own goal line. A possible safety scenario has a player for the offense going out of bounds, being tackled, or fumbling the ball out of bounds in his own end zone, resulting in the ball becoming dead behind his own goal line. The safety results in two points being awarded to the opponent team (in this case the defense).
Another possible safety scenario involves a player of the defense gaining possession of the ball in front of his own team’s goal line, then carrying the ball or fumbling it back behind his own goal line in a way that results in the ball becoming dead. In this case, the safety results in two points being awarded to the player’s opponents (the team originally on the offense).
If a team carrying out the offense is found to have committed a holding foul in its own end zone, it is penalized with a safety. (In football the term safety is also used in a different manner, as the name of a defensive player position.)
A touchback occurs when an offensive player fumbles the football into the opposing team’s end zone, and then the ball goes out of bounds. No points are scored. The opposing team gains control of the ball and starts play with a first down at their own 20-yard line.
A touchback also occurs if the ball becomes dead behind the goal line of the team in possession and the opponent team is responsible for the ball being there. No points are scored. The team last in possession keeps possession with a first down at its own 20-yard line. A possible scenario involves the defense intercepting a pass in its own end zone and then the ball becoming dead before being taken out of the end zone.
Following a football kick, if the opposing team’s kick returner catches the ball in his own end zone, he can either run with the ball, or kneel in the end zone to elect a touchback. A touchback also occurs when the kick goes out of bounds in the end zone.
A fumble occurs when a player drops a ball in play. Any player (defense or offense) who picks up a fumble can advance the ball, even if it has hit the ground. If a player loses his grip on the ball it may be grabbed out of the air by another player, who can run with it.
Fumbled balls that bounce forward and are then covered by the offensive team are returned to the fumbling team. Play resumes at the position of the fumble. If the fumbled ball moves out of bounds in the opponent’s end zone it results in a touchback.
In college football, if the defensive team intercepts or recovers a fumble during a conversion attempt and then takes the ball all the way to the opposing end zone, it is awarded two points.
Fouls are a type of rule violation that may result in penalties for the responsible team. Game officials are responsible for detecting fouls and assigning appropriate penalties.
Penalties typically involve moving the football towards the offending team’s end zone a specified distance. If the penalty would result in the ball being moved more than half the distance towards the offending team’s end zone, the penalty is made half the distance to the goal instead of its standard distance.
Many fouls lead to penalties resulting in replaying the down where they took place. Defensive fouls can result in penalties giving the offense an automatic first down, and some offensive penalties can result in loss of a down. A penalty of sufficient magnitude can result in the offensive team gaining a first down.
If a foul takes place after play has begun during a down, play is continued and an official throws a yellow penalty flag at the position of the foul. When the down ends, the team not responsible for the foul has the option of agreeing with the penalty against the other team, or declining the penalty and accepting the result of the down as played.
Although each football team is only allowed 11 players on the field at one time, the total number of players in a team is significantly higher. Teams typically have players only assigned to the offense or defense. There are also players with special functions, and players that serve as potential replacements for injured or otherwise temporarily unavailable team members.
Professional teams usually have over forty active players that can in theory play in any one game. A team can replace players between plays, and this is often done to place a player on the field that is best suited to the circumstances. The National Football League limits the roster of each team to a maximum of 53 players.
Football players wear jerseys and pants with built-in protective pads. The uniforms have distinctive team colors. The jerseys are marked with the team name and player name and number. Players wear helmets with face guards to protect them from face and head injuries.
The eleven players of the offense are broken into two groups: five offensive linemen, whose principal job is to block, and six receivers and backs whose main job is to advance the ball by either running with the ball or passing it to another offensive player. Offense linemen are normally not eligible to advance the ball during play. The backs and receivers are commonly eligible ball carriers.
Football rules specify that there must always be exactly seven players on the line of scrimmage and four players (backs) behind the line of scrimmage. Only the four backs and the two players on the end of the line are permitted to handle the ball during normal play. The other five players are considered ineligible, and may only block. Thus, during normal play, offensive linemen do not handle the ball, unless the ball is fumbled by a ball carrier. But the coach may switch a player who is normally a lineman to a different position better suitable for a particular play. Linemen are usually the largest and heaviest players on the field. Their positions require more strength and less speed than backs or wide receivers.
The center is the player who begins the play from scrimmage by passing the ball to the quarterback. The center usually plays in the middle of the offensive line and is responsible for blocking defensive players. The center often is also responsible for calling out blocking assignments and making last moment adjustments depending on the defense’s alignment.
Two guards position themselves on either side of the center. Their function is to block defensive players on both running and passing plays. On some plays, rather than blocking straight ahead, a guard may move out of his position in the line to lead block for a player carrying the ball.
The role of the two offensive tackles is primarily to block on both running and passing plays. The tackles are typically large and powerful players. They are positioned outside of the guards. The area from one tackle to the other is an area of close line play in which blocks from behind are permitted. Blocks from behind are prohibited elsewhere on the field. One tackle is particularly responsible for protecting the quarterback from being hit from behind (the quarterback’s blind side). This is the left tackle for a right-handed quarterback, or the right tackle for a left-handed quarterback.
Tight ends usually play outside of the tackles. They are often considered a hybrid position with the characteristics and roles of both an offensive lineman and a wide receiver. Like offensive linemen, they are usually lined up on the offensive line and are large enough to be effective blockers. Although tight ends are usually slower than wide receivers, they are eligible receivers capable of catching passes and running with the ball. The position known as the H-back is a tight end who lines up behind the line of scrimmage, and is thus counted as one of the four backs, but otherwise functions similarly to other tight ends.
The designations of the “back” positions are traceable to arrangements common in the early days of football. At that time, the quarterback began play a quarter of the way back, the halfbacks were positioned halfway back, side by side, and the fullback started play the furthest back.
Running backs line up behind the offensive line. They position themselves to receive the ball from the quarterback and carry out a rushing play. Up to three running backs may be used on a play. There are different types of running backs. The halfback is often the primary ball carrier on rushing plays. Halfbacks may also catch passes. The fullback, often larger and stronger than the halfback, acts principally as a blocker, but may also catch passes or advance the ball by running. Fullbacks often line up closer to the line of scrimmage than halfbacks, and may block for them.
The wide receivers are fast-running pass-catching specialists. They are sometimes called on to block, but their principal task is to position themselves for a pass, receive the ball, and run as far as they can toward the opponent’s end zone. Wide receivers generally take positions near the sidelines at the start of play. A wide receiver taking a position on the line of scrimmage is called a split end, and is one of the seven required players on the line of scrimmage. A wide receiver that positions himself behind the line of scrimmage is called a flanker, and is counted as one of the four backs. It is also possible for a wide receiver (a slot receiver) to take a position in the slot between the offensive line and the outmost wide receiver.
The quarterback is the leader of the offense and must have the ability to make quick decisions under stress. He is the player who receives the ball from the center at the start of the play. The quarterback is usually responsible for receiving instructions from the coaches on the sideline and communicating the play to the other offensive players in the huddle. The quarterback may need to make changes to the planned play at the line of scrimmage in response to his assessment of the defensive arrangement. This is done via an “audible,” a yelled code phrase (such as “green two”) to team members.
If at the start of play the quarterback takes a position some distance behind the center, he is considered to be “in the shotgun.” If positioned directly in contact with the center, and if he receives the ball via a hand-to-hand pass, the quarterback is considered “under center.” Upon receiving the ball, the quarterback may hand it to another player eligible to carry the ball to run with it, may keep the ball and run with it, may execute a forward pass to a player down the field, or may throw a lateral pass.
The defensive team or defense is the team that begins a play from scrimmage not in possession of the ball. The object of the defensive team is to prevent the other team from scoring. The defense accomplishes this by forcing the offense to turn the ball over, either by preventing them from achieving a first down and forcing a punt, or by forcing the offense to fumble or throw an interception.
Defensive linemen (tackles and ends) line up directly on the line of scrimmage, facing their offensive counterparts.
Defensive tackles play at the center of the defensive line. There are usually two defensive tackles. Their principal tasks are to stop running plays at the center of the line of scrimmage, and to penetrate the offensive line and rush players attempting to pass the ball. Defensive tackles who line up directly across from the ball, facing the offense’s center, are called nose tackles.
Defensive ends play next to the defensive tackles, on the outer sides of the defensive line. Their task is to stop or contain offensive runs on the outer sides of the line of scrimmage, and to rush offensive players attempting to pass the ball. The faster defensive end is usually positioned on the right side of the defensive line, since this is a right-handed quarterback’s blind side.
Linebackers are players that take positions behind the defensive line. The middle linebacker is often the leader of the defense. He carries out various tasks, as appropriate to particular situations. His functions include stopping offensive players who penetrate the defensive line and rushing offensive players attempting to pass the ball.
Outside linebackers position themselves to either side of the middle linebacker. Their tasks include defending against offensive runners, covering the tight ends or running backs on pass plays, and rushing the quarterback.
Defensive backs play behind the linebackers or near the sidelines. They are normally composed of two cornerbacks and two safeties. Cornerbacks typically cover the wide receivers. Their tasks include preventing passes from reaching the receivers, if possible by catching the passes, and containing runners of the offense. Defensive backs may tackle runners or cause them to go out of bounds.
Safeties typically play at the rear of the defense, closer to the middle of the field than the cornerbacks. The larger and stronger of the two safeties, the strong safety, provides deep-pass coverage and defends against running plays on the tight end side of the field. The other safety, the free safety, is a fast runner that sometimes assumes the rearmost defensive position. The free safety helps defend against the longer passing attempts.
Some players have special functions carried out during kicking plays (kickoffs, field goal attempts, and punts). The player that holds the ball for the kicker to kick is called the holder. The holder usually positions himself about seven yards from the line of scrimmage. The kicker kicks the football held by the holder or resting on a kicking tee.
The punter is a player whose function is to punt. The punter drops the ball and kicks it while it falls. A long snapper is a special player at the center position on kicking plays. His function is to snap the ball to the holder or the punter.
Upbacks are players whose functions include calling for the snap to be received by the punter and protecting the punter from advancing defensive players.
Punt and kick returners are specially fast runners whose function is to catch the kicked football and run with it as far as possible toward the opponent’s end zone.
The gunner is a player specializing on running down and tackling kick returners. The gunner often takes a position near the sidelines where he may be better able to run free of blockers.
The conduct of the game of football is overseen by officials responsible for proper game performance, timekeeping, and rule enforcement. The officials wear distinctive uniforms, typically white shirts with thick vertical black stripes, white baggy pants (knickerbockers), and black belt and shoes. In professional and college games, officials include the referee, umpire, head linesman, line judge, side judge, back judge, and field judge. In high school football, a smaller number of officials may be used.
The referee is responsible for overall game supervision. The umpire identifies occurrences of illegal play, monitors the number of offensive players, and checks the legality of player equipment. The head linesman monitors for infractions, determines whether a player is out of bounds, and is responsible for marking the progress of the ball.
The line, side, back and field judges take different positions around the players, judge the actions of the players, and have specific responsibilities to enforce rules and monitor the progress of the game. The back judge and the field judge rule whether field goal attempts are successful and have timekeeping responsibilities.
Most football teams include a cheerleading squad in their organization or are associated with a cheerleading group. Cheerleaders provide entertainment in support of their teams and their fans. They are selected based on their dance ability, athleticism, appearance, and personal accomplishments.
Cheerleaders wear distinctive team-specific uniforms. On the field, they perform dance routines, cheers, and stunts. They also make community service appearances and, in professional football, often appear in team promotional advertisements.
High school, college and professional football games are played according to rules instituted by appropriate national and regional organizations. The National Football League official rulebook specifies national league rules. The National Collegiate Athletic Association issues rules governing college football.