In American football, each team has 11 players on the field at one time. However, because the rules allow unlimited substitution between plays, the types of players on the field for each team differ depending on the situation. In the NFL, most play only offense or only defense, with "two-way" players being of the long-ago past.
The offensive team or 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, or runs the ball himself. The object of the offensive team is to score points for their team. 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 American 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.
- Center—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.
- Guard—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—the offensive tackles play on either side of the guards. 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 cannot catch or run the ball in most circumstances. 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—tight ends play on either side of, and immediately 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 end tight and one split end. Many modern formations forego tight ends and replace them with wide receivers. Sometimes a formation is referred to as having "three tight ends", which in reality means an additional blocker (a wingback or an eighth lineman) has been substituted for a wide receiver, as in short-yardage situations.
- Wide receiver—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, be a deep threat, and to not allow the defense to bring an eighth man near the line of scrimmage to discourage or defeat rushing plays. 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—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 use.
- Running back—the modern term for the position formally 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—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." This variation was first used by former Niner Head Coach Bill Walsh, who used tackle Guy McIntyre as a receiver. A few years later tackle William Perry scored a touchdown in Super Bowl XX. Jumbo Ellott and Dan Klecko are two other tackles who have caught touchdowns while being tackle eligible.
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 4th 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 American 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 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 employe 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 four 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.
Typically, a team will have a safety who also has a reputation of being a hard hitter, as evidenced by Mark Carrier, Rodney Harrison and Bob Sanders, John Lynch, and Sean Taylor to name a slim few. More recently, teams are looking for hybrid safeties who can do both jobs, as in a cover 2 defense, the strong safety has a greater role to play in coverage. Safeties are also used in a variety of blitzes.
- Nickel- and Dime- backs—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 runningbacks 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.
Special teams are units that are on the field during kickoffs, free kicks, punts, and 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)—Not a real player, just handles kickoffs and field goal attempts.
- Holder—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—a specialized center who snaps the ball directly to the holder. The long snapper is often a backup tight end.
- Kick returner (KR)—returns kickoffs.
- Punter (P)—kicks punts.
- Punt returner (PR)—returns punts.
- Gunner—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—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.
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.
For the purposes of scoring in fantasy football, points scored on special team returns are typically credited to the defense.
|Positions in football|
|Linemen||Guard, Tackle, Center||Linemen||Tackle, End, Nose tackle||Kicking players||Placekicker, Punter|
|Quarterback||Linebackers||Snapping||Long snapper, Holder|
|Backs||Running back, Fullback, H-back||Backs||Cornerback, Safety||Returning||Punt returner, Kick returner|
|Receivers||Wide receiver, Tight end||Nickelback, Dimeback||Tackling||Gunner|