Physicality

A halfback leads fellow backs through an agility drill at the Air Force Academy

American football is a collision sport. To stop the offense from advancing the ball, the defense must tackle the player with the ball by knocking or pulling him down. As such, defensive players must use some form of physical contact to bring the ball-carrier to the ground, within certain rules and guidelines. Tacklers cannot kick or punch the runner. They also cannot grab the face mask of the runner's helmet or lead into a tackle with their own helmet. Despite these and other rules regarding unnecessary roughness, most other forms of tackling are legal. Blockers and defenders trying to evade them also have wide leeway in trying to force their opponents out of the way. Quarterbacks are regularly hit by defenders coming on full speed from outside the quarterback's field of vision. This is commonly known as a blindside.

To compensate for this, players must wear special protective equipment, such as a padded plastic helmet, shoulder pads, hip pads and knee pads. These protective pads were introduced decades ago and have improved ever since to help minimize lasting injury to players. An unintended consequence of all the safety equipment has resulted in increasing levels of violence in the game. Players may now hurl themselves at one another at high speeds without a significant chance of injury. The injuries that do result tend to be severe and often season or career-ending and sometimes fatal. In previous years with less padding, tackling more closely resembled tackles in Rugby football. Better helmets have allowed players to use their helmets as weapons. This form of tackling is particularly unwise, because of the great potential for brain or spinal injury. All this has caused the various leagues, especially the NFL, to implement a complicated series of penalties for various types of contact. Most recently, virtually any contact with the helmet of a defensive player on the quarterback, or any contact to the quarterback's head, is now a foul.

Despite protective equipment and rule changes to emphasize safety, injuries remain very common in football. It is increasingly rare, for example, for NFL quarterbacks or running backs (who take the most direct hits) to make it through an entire season without missing some time to injury. Additionally, 28 football players, mostly high schoolers, died from direct football injuries in the years 2000-05 and an additional 68 died indirectly from dehydration or other examples of "non-physical" dangers, according to the National Center for Catastrophic Sport Injury Research.^[11] Concussions are common, with about 41,000 suffered every year among high school players according to the Brain Injury Association of Arizona. In 1981, former U.S. President Ronald Reagan, who played football in high school, commented on the contact of the sport: "[Football] is the last thing left in civilization where men can literally fling themselves bodily at one another in combat and not be at war."

Extra and optional equipment such as neck rolls, spider pads, rib protectors (referred to as "flak jackets"), and elbow pads help against injury as well, though they do not tend to be used by the majority of players due to their lack of requirement.

The danger of football and the equipment required to reduce it make regulation football impractical for casual play. Flag football and touch football are less violent variants of the game popular among recreational players.

Basic strategy

Because the game stops after every down, giving teams a chance to call a new play, strategy plays a major role in football. Each team has a playbook of dozens to hundreds of plays. Ideally, each play is a scripted, strategically sound team-coordinated endeavor. Some plays are very safe; they are likely to get only a few yards. Other plays have the potential for long gains but at a greater risk of a loss of yardage or a turnover.

Generally speaking, rushing plays are less risky than passing plays. However, there are relatively safe passing plays and risky running plays. To deceive the other team, some passing plays are designed to resemble running plays and vice versa. These are referred to as play-action passes and draws. There are many trick or gadget plays, such as when a team lines up as if it intends to punt and then tries to run or pass for a first down. Such high-risk plays are a great thrill to the fans when they work. However, they can spell disaster if the opposing team realizes the deception and acts accordingly.

The defense also plans plays in response to expectations of what the offense will do. For example, a "blitz" (using linebackers or defensive backs to charge the quarterback) is often attempted when the team on defense expects a pass. A blitz makes downfield passing more difficult but exposes the defense to big gains if the offensive line stems the rush.

Many hours of preparation and strategizing, including film review by both players and coaches, go into the days between football games. This, along with the demanding physicality of football (see below), is why teams typically play at most one game per week.

Special teams

"Special teams" redirects here. For the ice hockey definition of "special teams," see powerplay and short handed.

Special teams are units that are on the field during kickoffs, free kicks, punts, field goal and extra point attempts. Most special teams players are second- and third-string players from other positions.

Special teams are unique in that they can serve as offensive or defensive units and that they are only seen sporadically throughout a game.

Special teams include a kickoff team, a kick return team, a punting team, a punt blocking/return team, a field goal team and a field goal block team.

There are also specialized players on these teams, including:

• Kicker (K) — Handles kickoffs and field goal attempts, and in some leagues, punts as well.
• Holder (H) — Usually positioned 7-8 yards from the line of scrimmage, he holds the ball for the placekicker to kick. The holder is often a backup quarterback or a punter.
• Long snapper (LS) — A specialized center who snaps the ball directly to the holder or punter. The long snapper is often an offensive linemen or backup Tight End; rarely a center.
• Kick returner (KR) — Returns kickoffs, generally is also a wide receiver or cornerback.
• Punter (P) — Kicks punts. In leagues other than the NFL, the kicker often doubles as the punter.
• Upback — A blocking back that lines up approximately 1-3 yards behind the line of scrimmage in punting and kneel situations. His primary job is to act as a second line of defense for the punter. Upbacks can receive a direct snap in fake punt situations.
• Punt returner (PR) — Returns punts. Often the same player as the kick returner, although not necessarily so.
• Gunner — A player on kickoffs and punts who specializes in running down the field very quickly in an attempt to tackle the kick returner or the punt returner.
• Wedge Buster — A player whose goal is to sprint down the middle of the field on kickoffs. While ideally, their goal is to reach the kick returner, their immediate goal is to disrupt the wall of blockers (the wedge) on kickoffs, preventing the returner from having a lane in which to get a substantial return. Being a wedge buster is a very dangerous position since he may often be running at full speed when coming into contact with a blocker.
• Hands Team — Used only during onside kicks, the members of a hands team are responsible for preventing the kicking team from recovering a kick, usually by recovering the ball themselves.

Because these aspects of the game can be so different from general offensive and defensive play, a specific group of players is drilled in executing them. Though fewer points are scored on special teams than on offense, special teams play determines where the offense will begin each drive, and thus it has a dramatic impact on how easy or difficult it is for the offense to score.

Defense

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 sign that the defensive goal has been accomplished is a fourth down, which usually involves punting the ball.

Unlike the offensive team, there are no formally defined defensive positions. A defensive player may line up anywhere on his side of the line of scrimmage and perform any legal action. However, most sets used in football include a line composed of defensive ends and defensive tackles and (behind the line) linebackers, cornerbacks, and safeties.

Defensive ends and tackles are collectively called defensive line, while the cornerbacks and safeties are collectively called the secondary, or defensive backs.

• Defensive end (DE) — The two defensive ends play on opposite outside edges of the defensive line. Their function is to attack the passer or stop offensive runs to the outer edges of the line of scrimmage (most often referred to as "containment"). The faster of the two is usually placed on the right side of the defensive line (quarterback's left) because that is a right-handed quarterback's blind side.

• Defensive tackle (DT) — Sometimes called a defensive guard, defensive tackles are side-by-side linemen who are between the defensive ends. Their function is to rush the passer (if they can get past the offensive linemen blocking them), and stop running plays directed at the middle of the line of scrimmage. A defensive tackle that lines up directly across from the ball (and therefore, is almost nose-to-nose with the offense's center) is often called a nose tackle or nose guard. The nose tackle is most common in the 3-4 defense and the quarter defense. Most defensive sets have from one to two defensive tackles. Sometimes, but not often, a team will employ three defensive tackles.

• Linebacker (LB) — Linebackers play behind the defensive line and perform various duties depending on the situation, including rushing the passer, covering receivers, and defending against the run. Most defensive sets have between two and three linebackers. Linebackers are usually divided into three types: strongside (left or right outside linebacker: LOLB or ROLB); middle (MLB); and weakside (LOLB or ROLB). The strongside linebacker usually lines up across from the offense's tight end; he is usually the strongest LB because he must be able to shed lead blockers quickly enough to tackle the running back. The middle linebacker must correctly identify the offense's formations and what adjustments the entire defense must make. Because of this, the middle linebacker is nicknamed the "quarterback of the defense". The weakside linebacker is usually the most athletic or fastest linebacker because he usually must defend an open field.

• Cornerback (CB) — Typically two players that primarily cover the wide receivers. Cornerbacks attempt to prevent successful quarterback passes by either swatting the airborne ball away from the receiver or by catching the pass themselves. In rushing situations, their job is to contain the rusher.

• Safety (FS or SS) — The safeties are the last line of defense (farthest from the line of scrimmage) and usually help the corners with deep-pass coverage. The strong safety (SS) is usually the larger and stronger of the two, providing extra protection against run plays by standing somewhere between the free safety and the line of scrimmage. The free safety (FS) is usually the smaller and faster of the two, providing variable and extra pass coverage. Traditionally, teams have looked for safeties with reputations as hard hitters. More recently, however, teams have been looking for hybrid safeties who can do both jobs, as in a cover 2 defense, when the strong safety has a greater role to play in coverage. Safeties are also used in a variety of blitzes.

Defensive back — It is not a specific position, however, it is any position besides the line, including cornerbacks, safeties, etc., that is behind the line of scrimmage.

• Nickelback and Dimeback — In certain formations one extra (a fifth) defensive back (called a nickel defense), two extra (a sixth) DB (called a Dime package), or even three extra (a seventh) DB called a Quarter may be used to augment the backfield or defensive line. Nickelbacks, dimebacks, and Defensive Quarterbacks are usually used to defend pass plays with extra receivers, but they can also be used to rush quarterbacks or running backs more quickly than linemen or most linebackers can. A starting cornerback who is good at blitzing and tackling will sometimes be referred to as a nickelback to distinguish them from cornerbacks.

Offense

The offensive team or offense in football is the team that begins a play from scrimmage in possession of the ball. A play usually begins when the quarterback takes a snap from the center and then either hands off to a back, passes to a receiver or a back, runs the ball himself, spikes the ball, or takes a knee.

The purpose of spiking the ball is to stop the play clock if the offense is running out of time. The purpose of taking a knee is to waste time. If a player runs the ball and stays in bounds, or if a player receives a pass and stays in bounds (this has the same effect as taking a knee), then the clock keeps ticking. But if a player runs out of bounds, or there is an incomplete pass (this also counts as spiking the ball), then the clock stops.

Usually the sign that their goal is accomplished for the offensive team is the touchdown. However, the offensive team can also help the team score by getting good field position for an attempt at a field goal.

The offensive unit in football consists of a quarterback, linemen, backs, tight ends and receivers. The function of most of the linemen is to block. The offensive line consists of a center, two guards, two tackles and one or two tight ends. Backs include running backs (or tailbacks) who frequently carry the ball, and a fullback, who usually blocks, and occasionally carries the ball or receives a pass. The primary function of the wide receivers is to catch passes.

The ultimate makeup of the offense and how it operates is governed by the head coach or offensive coordinator's offensive philosophy.

• Center (C)—the center performs the normal blocking functions of all linemen and is the player who puts the ball in play by means of the snap.
• Offensive guard (OG)—the two guards are the offensive linemen directly on either side of the center and inside the tackles. Like all interior linemen, their function is to block on both running and passing plays. On some plays, rather than blocking straight ahead, a guard will "pull" - moving around behind the other offensive linemen upon the start of the play - in order to block a player on either side of the center, in an inside running play called a "trap" or an outside running play called a "sweep".
• Offensive tackle (OT)—the offensive tackles play on both of the guards outside. Their role is primarily to block on both running and passing plays. The area from one tackle to the other is an area of "close line play" in which some blocks from behind, which are prohibited elsewhere on the field, are allowed. For a right-handed quarterback, the left tackle is charged with protecting the blindside, and is often faster than the other offensive linemen to stop 'speed rushers' at the Defensive End position. Like a guard, the tackle may have to "pull", on a running play, when there is a tight end on his side.

The description above of the guard and tackle positions apply only to a line that is balanced (has equal numbers of players on both sides of the player who is to snap the ball). In an unbalanced line, there may be players designated "guard" or "tackle" next to each other.

Offensive linemen can not catch the ball but may run the ball if they want. In most circumstances, however, they do not. Except for the snap by the offensive center as each play from scrimmage starts, ordinarily the only way an offensive lineman can get the ball during a play is by picking up a fumble. On rare occasions offensive linemen legally catch passes; they can do so either by reporting as an eligible receiver to the referee prior to the snap or by catching a pass which has first been deflected or otherwise touched by an eligible receiver or a defensive player. Any other touching of the ball by an offensive lineman will result in a penalty.

• Tight end (TE) — Tight ends play on either side of, and roughly next to, the tackles. They are a mix between a blocker and a pass receiver. If an end moves away from the tackle, he is called a split end. Modern formations typically have one tight end and one split end. Many modern formations also forego tight ends and replace them with wide receivers. Sometimes a formation is referred to as having "three tight ends." This means in reality that an additional blocker (a wingback or an eighth lineman) has been substituted for a wide receiver. This would be done as in short-yardage situations where receivers are not needed.

• Wide receiver (WR) — The wide receivers are speedy pass-catching specialists. Their main job is to run pass routes and get open for a pass, although they are occasionally called on to block. A wide receiver may line up on the line of scrimmage and be counted as one of the necessary 7 players on the line in a legal formation (a split end), or he may line up at least one step behind the line of scrimmage and be counted as being in the backfield (a flanker if he is on the outside, a slot if he is not). There are generally two types of wide receivers, "speed" and "possession". A speed receiver's primary function is to stretch the field, to be a deep threat, and to pull away an eighth defensive man near the line of scrimmage from moves against the quarterback. A possession receiver is generally the more sure-handed of the two types and is used to keep possession of the ball by making catches that gain first down yardage, but he usually lacks the speed to attack a defensive backfield.

• Fullback (FB) — Positioned behind the middle of the line, a fullback may do some running, some blocking, and some short receiving. A classic fullback is more of a power runner than a running back. Many modern formations do not use a fullback. Most plays utilizing the fullback call for him to block, generally by running up the middle of the line, clearing a path for a running back to run while having the ball to gain yardage.

Penn State Nittany Lions quarterback #14 Anthony Morelli hands the ball off to his tailback #33 Austin Scott in their 2007 season opener.

• Running back (RB) — The modern term for the position formerly called "halfback". The running back carries the ball on most running plays and is also frequently used as a short-yardage receiver. Running backs, along with the wide receivers, are generally the fastest players on the offensive team. Most of them tend not to run straight ahead, preferring to make quick cutbacks to try to find holes in the defense. This, however, is a generalization, since some running backs are more power-oriented. "Fullback" is now regarded as a separate position from running back, with a substantially different role (especially in the NFL).

• Tailback (TB) — A running back that is positioned behind the middle of the line and deepest of all backs.

• H-back — A position that was popularized by Joe Gibbs during his first tenure with the Washington Redskins, the H-back is a hybrid position that combines the skill sets of fullback, tight end, and even wide receiver. An H-back lines up similarly to a slotback—but deeper and not as wide—and frequently serves as a blocker for a more deeply positioned back.

• Wingback — A player positioned just outside the outermost tight end, the wingback is slightly offset from the line of scrimmage which designates the position as wingback rather than tight end. The wingback is typically used in extreme blocking situations or unbalanced offensive formations.

• Slotback — A player positioned just outside the outermost offensive lineman, the slotback is slightly offset from the line of scrimmage which designates the position as a slotback rather than a tight end. The slotback is a typical position in flexbone formations and other Triple Option formations.

• Quarterback (QB) — Typically the quarterback is positioned to take a snap handed between the center's legs. However, recent usage refers imprecisely to a player who is positioned behind the center at any distance, calls signals, is not the usual punter or place kick holder, and usually takes the snap as "quarterback" regardless of exact position, because those functions have typically been performed by quarterbacks. Typical play from formations where the quarterback takes the snap proceeds by the quarterback either handing the ball off to a running back to run, throwing the ball downfield, or running personally.

Teams can vary the number of wide receivers, tight ends and running backs on the field at one time. Football rules limit the flexibility of offensive formations. Seven players must line up on the line of scrimmage, and only the two at the end are eligible to catch passes. Sometimes, offensive lineman can declare eligibility and become "tackle eligible." Jumbo Elliott and Dan Klecko are two tackles who have caught touchdowns while being tackle eligible. Typical formations include:

• One running back, two tight ends and two wide receivers.
• Two running backs, one tight end and two wide receivers.
• One running back, one tight end and three wide receivers.
• One running back, no tight end and four wide receivers.
• No running backs, no tight end and five wide receivers.

A Common Youth and High School Formation is different but effective.

Cambridge University Football Club

The playing of football had always been popular in Cambridge and in 1579 one match played at Chesterton between townspeople and Cambridge University students ended in a violent brawl that led the Vice-Chancellor to issue a decree forbidding them to play "footeball” outside of college grounds. Despite this and other decrees, football continued to be popular in Cambridge, as Dr. G.E. Corrie, Master of Jesus College, observed in 1838, "In walking with Willis we passed by Parker's Piece and there saw some forty Gownsmen playing at football. The novelty and liveliness of the scene were amusing!" . As a result of its role in the formation of the first football rules, Parker's Piece, Cambridge, remains hallowed turf for football fans and historians.

In 1846, H. de Winton and J.C. Thring, who had both attended Shrewsbury School, succeeded in making some old Etonians join them to form a football club at Cambridge University. Only a few matches were ever played, but in 1848 interest in the sport was renewed. The story of how the 1848 rules were formulated was related by Mr H.C. Malden in a letter dated 8 October 1897.

I went up to Trinity College Cambridge. In the following year an attempt was made to get up some football in preference to the hockey that was then in vogue. But the result was dire confusion, as every man played the rules he had been accustomed to at his public school. I remember how the Eton men howled at the Rugby men for handling the ball. So it was agreed that two men should be chosen to represent each of the public schools, and two who were not public school men, for the 'Varsity. G. Salt and myself were chosen for the 'Varsity. I wish I could remember the others. Burn of Rugby, was one; Whymper of Eton, I think, also. We were 14 in all I believe. Harrow and Eton Rugby, Winchester, Shrewsbury were represented. We met in my rooms after Hall, which in those days was at 4.pm.; anticipating a long meeting, I cleared the tables and provided pens, ink and paper. Several asked me on coming in whether an exam was on! Every man brought a copy of his school rules, or knew them by heart, and our progress in framing new rules was slow. On several occasions Salt and I, being unprejudiced, carried or struck out a rule when the voting was equal. We broke up five minutes before midnight. The new rules were printed as the "Cambridge Rules", copies were distributed and pasted up on Parker's Piece, and very satisfactorily they worked, for it is right to add that they were loyally kept, and I never heard of any public school man who gave up playing from not liking the rules. [...] Well Sir, years afterwards someone took these rules, still in force at Cambridge, and with a very few alterations they became the Association Rules. A fair catch, free kick (as still played at Harrow) was struck out. The offside rule was made less stringent. "Hands" was made more so; this has just been wisely altered.

The creators of the Cambridge rules sought to formulate a game that was acceptable to students who had played various codes of public school football. The public school games included a wide range of rules, from the Rugby game (with ball handling and backwards passing) through the Eton game (which favoured dribbling and had a tight offside rule) to the Charterhouse football (that involved dribbling and whose representatives favoured rules permitting forward passing). The Off-side rule adopted by the Cambridge rules stated that:

"If the ball has passed a player and has come from the direction of his own goal, he may not touch it till the other side have kicked it, unless there are more than three of the other side before him. No player is allowed to loiter between the ball and the adversaries' goal(1856, probably earlier)

This rule was subsequent adopted by the Football Association in 1867. This off-side rule, which permitted players to move in front of the ball opened the way to the subsequent development of the Combination Game.

The Cambridge Rules were the first formulated rules of football and the predecessor of modern Association Football. They were very influential in the creation of the modern rules of soccer drawn up in London by Ebenezer Cobb Morley for the Football Association, as shown in the following praise:

'The Cambridge Rules appear to be the most desirable for the Association to adopt'—C. W. Alcock 1863, FA Committee Member and founder of the FA Cup.

'They embrace the true principles of the game, with the greatest simplicity'—E. C. Morley, F.A. Hon. Sec. 1863.

A plaque has been mounted at Parker's Piece, Cambridge to document its unique role in the creation of modern football. It bears the following inscription:

Here on Parker's Piece, in the 1800s, students established a common set of simple football rules emphasising skill above force, which forbade catching the ball and 'hacking'. These 'Cambridge Rules' became the defining influence on the 1863 Football Association rules.

Sheffield Rules

The Sheffield Rules was a code of football devised and played in the English city of Sheffield between 1857 and 1877. They were devised by Nathaniel Creswick and William Prest for use by the newly founded Sheffield Football Club. The rules were subsequently adopted as the official rules of Sheffield Football Association upon its creation in 1867. They spread beyond the city boundaries to other clubs and associations in the north and midlands of England making them one of the most popular forms of football during the 1860s and 70s.

Six years after the creation of the Sheffield Rules the Football Association rules were created. These were influenced by the Sheffield game but ongoing disputes meant that the Sheffield rules continued to be used. During this time many of the elements of the rules were incorporated in to the association game. Regular games were played between Sheffield and London using both sets of rules. This led to an agreement on a single set of laws administered by the Football Association in 1877.

The rules had a major influence on how the modern game of football developed. Among other things they introduced the concept of free kicks for fouls, corners and throw-ins into the laws of the game. The abolition of the fair catch also led to their teams to be the first to head the ball. Games played under the rules are also accredited for the development of heading and the origins of the goalkeeper and forward positions. The first inter-club football match and competitive tournament were both played using Sheffield Rules.