Science Fair Project Encyclopedia
The offensive team or offense in American football or Canadian football, is the team that begins a play from scrimmage in possession of the ball. A play usually begins with the quarterback taking a snap from the center, and then either handing off to a back, passing to a receiver or a back, or running the ball himself.
The offensive unit in American football consists of a quarterback, linemen, backs, and receivers. The function of most of the linemen is to block. The line consists of a center, two guards, two tackles and one or two 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, in addition, 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" 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".
- 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.
Note that the description above of the guard and tackle positions apply only to a line that is balanced, i.e. that 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.
- 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, the other split. Many modern formations dispense with tight ends completely, replacing 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 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 off the line of scrimmage and be counted as being in the backfield (a flanker). 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 cheat and bring an eighth man into the box. 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 lacks the raw 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 straight-ahead, "four yards and a cloud of dust" 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 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, as 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 - 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 wingback, but deeper and not as wide, and frequently serves as a blocker for a more deeply positioned back.
- wingback - a player positioned just outside of behind the outermost lineman who is not split from the rest of the line; if no linemen are split, then the wingback position is just outside of and behind the (tight) end.
- quarterback - a player positioned close to and behind an interior lineman. 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. See quarterback.
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