Canadian football is a sport played in Canada in which two teams of 12 players each compete for territorial control of a field of play 110 yards (101 m) long and 65 yards (59 m) wide attempting to advance a pointed oval-shaped ball into the opposing team's scoring area.
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.
The quarterback, colloquially known as the "signal caller", is a position in gridiron football. Quarterbacks are members of the offensive platoon 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 shotgun formation is a formation used by the offensive team in gridiron football mainly for passing plays, although some teams use it as their base formation. Instead of the quarterback receiving the snap from center at the line of scrimmage, in the shotgun he stands farther back, often five to seven yards off the line. Sometimes the quarterback will have a back on one or both sides before the snap, while other times he will be the lone player in the backfield with everyone spread out as receivers.
In gridiron football, a lineman is a player who specializes in play at the line of scrimmage. The linemen of the team currently in possession of the ball are the offensive line, while linemen on the opposing team are the defensive line. A number of NFL rules specifically address restrictions and requirements for the offensive line, whose job is to help protect the quarterback from getting sacked for a loss, or worse, fumbling. The defensive line is covered by the same rules that apply to all defensive players. Linemen are usually the largest players on the field in both height and weight, since their positions usually require less running and more strength than skill positions.
A wide receiver (WR), also referred to as a wideout, 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.
The tight end (TE) is an offensive position in American football, arena football, and Canadian football. It is a hybrid that combines the characteristics and roles of both an offensive lineman and a receiver. Like offensive linemen, they are usually lined up on the offensive line and are large enough to be effective blockers. On the other hand, unlike offensive linemen, they are eligible receivers and potent weapons in team's offensive schemes.
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.
Strategy forms a major part of American football. Both teams plan many aspects of their plays (offense) and response to plays (defense), such as what formations they take, who they put on the field, and the roles and instructions each player are given. Throughout a game, each team adapts to the other's apparent strengths and weaknesses, trying various approaches to outmaneuver or overpower their opponent in order to win the game.
Gameplay in American football consists of a series of downs, individual plays of short duration, outside of which the ball is dead or 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.
In football, the tackle-eligible play is a forward-pass play in which coaches will attempt to create mismatches against a defense by inserting an offensive tackle, into an offensive formation as an eligible receiver, usually as a tight end or as a fullback. This is done by changing the formation of the offensive line, via positioning two linemen on one side of the center and three linemen on the other.
In American football, the specific role that a player takes on the field is referred to as their "position". Under the modern rules of American football, both teams are allowed 11 players on the field at one time and have "unlimited free substitutions", meaning that they may change any number of players during any "dead ball" situation. This has resulted in the development of three task-specific "platoons" of players within any single team: the offense, the defense, and the so-called 'special teams'. Within these three separate "platoons", various positions exist depending on the jobs that the players are doing.
In American football, a play is a close-to-the-ground plan of action or strategy used to move the ball down the field. A play begins at either the snap from the center or at kickoff. Most commonly, plays occur at the snap during a down. These plays range from basic to very intricate. Football players keep a record of these plays in a playbook.
The offensive backfield is an ambiguous generic term of football, which includes: (1) a place, namely the area of an American football field behind the line of scrimmage; and (2) a group classification of certain players positioned there, i.e., members of offense who begin plays behind the line, typically including any backs on the field, such as the quarterback, halfbacks and fullback. There are rules specific to the manner of play in that area.
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.
Wildcat formation describes a formation for the offense in football in which the ball is snapped not to the quarterback but directly to a player of another position lined up at the quarterback position. The Wildcat features an unbalanced offensive line and looks to the defense like a sweep behind zone blocking. A player moves across the formation prior to the snap. However, once this player crosses the position of the running back who will receive the snap, the play develops unlike the sweep.
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.
Players in the National Football League (NFL) wear uniform numbers between 0 and 99, with no two players on a team able to wear the same number outside of the offseason. Rules exist which tie a player's number to a specific range of numbers for their primary position. Additionally, rules exist which limit who may handle the ball on offense: generally players who are designated as offensive lineman, who wear numbers 50–79, are not allowed to handle the ball during a play from scrimmage, though they are allowed to do so if they report to the referee as playing out of position for a tackle-eligible play.
