In gridiron football, not all players on offense are entitled to receive a forward pass: only an eligible pass receiver may legally catch a forward pass, and only an eligible receiver may advance beyond the neutral zone if a forward pass crosses into the neutral zone. If the pass is received by a non-eligible receiver, it is "illegal touching". If an ineligible receiver is beyond the neutral zone when a forward pass crossing the neutral zone is thrown, a foul of "ineligible receiver downfield" is called. Each league has slightly different rules regarding who is considered an eligible receiver.
A snap is the backward passing of the ball in gridiron football at the start of play from scrimmage.
In gridiron football, a line of scrimmage is an invisible transverse line beyond which a team cannot cross until the next play has begun. Its location is based on the spot where the ball is placed after the end of the most recent play and following the assessment of any penalty yards.
The quarterback (QB) is a position in gridiron football who are members of the offensive side of the ball and mostly line up directly behind the offensive line. In modern American football, the quarterback is usually considered the leader of the offense, and is often responsible for calling the play in the huddle. The quarterback also touches the ball on almost every offensive play, and is almost always the offensive player that throws forward passes. When the QB is tackled behind the line of scrimmage, it is called a sack. The position is also colloquially known as the "signal caller" and "field general".
A cornerback (CB) is a member of the defensive backfield or secondary in gridiron football. Cornerbacks cover receivers most of the time, but also blitz and defend against such offensive running plays as sweeps and reverses. They create turnovers through hard tackles, interceptions, and deflecting forward passes.
A wide receiver (WR), also referred to as a wideout, and historically known as a split end (SE) or flanker (FL), is an eligible receiver in gridiron football. A key skill position of the offense, WR gets its name from the player being split out "wide", farthest away from the rest of the offensive formation.
This is a glossary of terms used in Canadian football. The Glossary of American football article also covers many terms that are also used in the Canadian version of the game.
- Legally positioned at the kick-off or the snap. On kick-offs, members of the kicking team must be behind the kick-off line; members of the receiving team must be at least 10 yards from the kick-off line. On scrimmages, at the snap the offence must be behind the line of scrimmage; the defence must be at least one yard beyond the line of scrimmage.
- A player of the kicking team who can legally recover the kick. The kicker and any teammates behind the ball at the time of the kick are onside. Thus on kick-offs all players of the kicking team are onside, but on other kicks usually only the kicker is. The holder on a place kick is not considered onside.
- A defensive position on scrimmages, also called free safety. Typical formations include a single safety, whose main duty is to cover wide receivers. See also defensive back.
- A two-point score. The defence scores a safety when the offence carries or passes the ball into its own goal area and then fails to run, pass, or kick the ball back into the field of play; when this term is used in this sense, it is also referred to as a safety touch.
American and Canadian football are gridiron codes of football that are very similar; both have their origins partly in rugby football, but some key differences exist between the two codes.
In American and Canadian football, pass interference (PI) is a foul that occurs when a player interferes with an eligible receiver's ability to make a fair attempt to catch a forward pass. Pass interference may include tripping, pushing, pulling, or cutting in front of the receiver, covering the receiver's face, or pulling on the receiver's hands or arms. It does not include catching or batting the ball before it reaches the receiver. Once the ball touches any defensive player or eligible offensive receiver, the above rules no longer apply and the defender may tackle the receiver or attempt to prevent them from gaining control of the ball. Once a forward pass is in the air it is a loose ball and thus any eligible receiver – all defensive players are eligible receivers – may try to catch it. When a defensive player catches a forward pass it is an interception and their team gains possession of the ball. Some actions that are defined as pass interference may be overlooked if the defender is attempting to catch or bat the ball rather than focusing on the receiver.
Gameplay in American football consists of a series of downs, individual plays of short duration, outside of which the ball is or is not in play. These can be plays from scrimmage – passes, runs, punts or field goal attempts – or free kicks such as kickoffs and fair catch kicks. Substitutions can be made between downs, which allows for a great deal of specialization as coaches choose the players best suited for each particular situation. During a play, each team should have no more than 11 players on the field, and each of them has specific tasks assigned for that specific play.
A formation in American football refers to the position players line up in before the start of a down. There are both offensive and defensive formations and there are many formations in both categories. Sometimes, formations are referred to as packages.
Center or centre (C) is a position in American football. The center is the innermost lineman of the offensive line on a football team's offense who passes the ball between his legs to the quarterback at the start of each play.
A trick play, also known as a gadget play, gimmick play or trickeration, is a play in gridiron football that uses deception and unorthodox tactics to fool the opposing team. A trick play is often risky, offering the potential for a large gain or a touchdown if it is successful, but with the chance of a significant loss of yards or a turnover if not. Trick plays are rarely used not only because of the riskiness, but also to maintain the element of surprise for when they are used.
Slotback, also called S-back or A-back, is a position in gridiron football. The "slot" is the area between the offensive tackle and the wide receiver. A player who lines up between those two players and behind the line of scrimmage fills that "slot".
The A-11 offense is an offensive scheme that has been used in some levels of amateur American football. In this offense, a loophole in the rules governing kicking formations is used to disguise which offensive players would be eligible to receive a pass for any given play. It was designed by Kurt Bryan and Steve Humphries of Piedmont High School in California.
The following terms are used in American football, both conventional and indoor. Some of these terms are also in use in Canadian football; for a list of terms unique to that code, see Glossary of Canadian football.
In gridiron football, an ineligible receiver downfield, or an ineligible man downfield, is a penalty called against the offensive team when a forward pass is thrown while a player who is ineligible to receive a pass is beyond the line of scrimmage without blocking an opponent at the time of the pass. A player is determined ineligible based on his position at the time of the snap. When the ball is snapped, the offense is required to have no more than eleven players on the field, out of whom only six are eligible. On most plays, the eligible receivers include the quarterback, running backs, fullbacks, tight ends, and wide receivers, while the ineligible receivers are offensive linemen, including the center, offensive guards, and offensive tackles. However, in the National Football League, a quarterback is an ineligible receiver if he is directly under the center when he receives the snap.
In gridiron football, a shift refers to the movement of an offensive player prior to the snap.
