In gridiron football, motion refers to the movement of an offensive player at the time of the snap.
While there are different rules regarding motion, most mandate that no more than one player may be in motion at the time of the snap,and the player must not be an offensive lineman (typically, the player in motion is a wide receiver or running back). Additionally, the NFL (professional), NCAA (college), and NFHSAA (high school) require that they be moving laterally or backwards; they are not allowed to be moving towards the line of scrimmage when the ball is snapped. The Canadian Football League and the Arena Football League allow for motion towards the line of scrimmage at the time of the snap.
There is a distinction drawn between a shift and motion in football. Motion occurs when a player is moving at the time of the snap. A shift occurs when one or more players changes their position on the offensive side of the ball before the snap, causing a change in formation.
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The National Football League defines all motion and shift penalties as "illegal motion",while both the NCAA and NFHSAA make a distinction between an "illegal shift" and "illegal motion"; an illegal shift refers to players shifting and not coming to a complete stop before the snap, while illegal motion refers to a player who is in motion towards the line of scrimmage, or a player who is not a "back" in motion. In both leagues, however, the penalty for illegal motion/illegal shift is five yards from the previous spot and replay the down.
Additionally, the offensive team may be charged with the penalty of a "false start" if a player on the offense jumps or moves abruptly, simulating the start of the play. This movement is not normally considered a subset of the "motion" or "shift" rules, as the player is not judged to be moving into a new pre-snap position; he is merely starting the play too soon. This is also a five-yard penalty.
In the earliest days of American football, offenses were allowed to shift and assemble themselves as much as they wanted as defenses are still allowed to do. The Minnesota shift and the Notre Dame Box were offensive systems of the early 20th century which relied heavily on shifting into new formations right before the play so that key players were already moving at the snap. However, rule changes were eventually implemented that banned wholesale formation shifts after the offensive team has lined up and required players to remain in that formation for at least one second before a snap or motion can occur.
One purpose for putting players in motion in the modern game is to gain clues about the defensive play call, particularly whether the defense is in "zone" or "man-to-man" coverage, as a defender assigned to cover a motioning offensive player will usually follow him across the formation. If the offensive team believes it knows the defense's cover scheme, it might audible to a play that is better suited to defeating the defense's strategy. Players in motion might also confuse a defense that does not communicate well, potentially leaving a pass receiver uncovered. The motion might also be used to allow an offensive player to start the play while already running at top speed parallel to the line of scrimmage such as in a flanker sweep play. In leagues that allow forward motion, receivers can begin the play already sprinting down the field, potentially allowing them to run past defenders.
In all forms of football, only players in the backfield and not on the line of scrimmage may be in motion at the time of the snap. Prior to starting the motion, all players on the offensive side must be in a set formation for a minimum of one second.
In most versions of American football, only one player may be in motion at one time, and the player must not move toward the line of scrimmage in his motion (in other words, he can only move laterally or backward). In no situation may the moving player begin on the line of scrimmage when he moves (in other words, offensive linemen are prohibited from motion prior to the snap). Any player who shifts from a lineman position to a back position must set in position at least five yards behind the line of scrimmage before going into motion.
Exceptions are as follows:
In leagues that allow forward motion, the moving player(s) cannot cross the line of scrimmage, otherwise a false start penalty is called.
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 backwards passing of the ball in gridiron football at the start of play from scrimmage.
In gridiron football, a line of scrimmage is an imaginary 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.
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 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, also referred to as a wideout, formerly a split end, is a ball-receiver in gridiron football. A key position, it gets its name from the player being split out "wide", farthest away from the rest of the offensive formation.
American and Canadian football are gridiron codes of football that are very similar; both have their origins in rugby football, but some key differences exist.
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.
In gridiron football, an official is a person who has responsibility in enforcing the rules and maintaining the order of the game.
A formation in 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.
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, sometimes referred to as an A-back or "slot receiver", is a position in gridiron football. The "slot" is the area between the last offensive lineman on either side of the center and the wide receiver on that side. A player who lines up between those two players and behind the line of scrimmage fills that "slot". The slotback position is a fixture of Canadian football and indoor football, but is also used in American football. The slotback requires a versatile player, who must combine the receiving skills of a wide receiver, the ball-carrying skills of a running back, and the blocking skills of a tight end.
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, a penalty is a sanction called against a team for a violation of the rules, called a foul. Officials initially signal penalties by tossing a bright yellow or orange colored penalty flag onto the field toward or at the spot of a foul. Many penalties result in moving the football toward the offending team's end zone, usually either 5, 10, or 15 yards, depending on the penalty. Most penalties against the defensive team also result in giving the offense an automatic first down, while a few penalties against the offensive team cause them to automatically lose a down. In some cases, depending on the spot of the foul, the ball is moved half the distance to the goal line rather than the usual number of yards, or the defense scores an automatic safety.
In 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.
In gridiron football, a punt is a kick performed by dropping the ball from the hands and then kicking the ball before it hits the ground. The most common use of this tactic is to punt the ball downfield to the opposing team, usually on the final down, with the hope of giving the receiving team a field position that is more advantageous to the kicking team when possession changes. The result of a typical punt, barring any penalties or extraordinary circumstances, is a first down for the receiving team. A punt is not to be confused with a drop kick, a kick after the ball hits the ground, now rare in both American and Canadian football.
In gridiron football, a shift refers to the movement of an offensive player prior to the snap.