In gridiron football, a shift refers to the movement of an offensive player prior to 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. For example, players may line up initially in an I-formation and then shift the two running backs into wide receiver positions to put the offense in a spread formation. A team may shift any number of players into new positions, so long as they all come to a complete stop for a full second before the ball is snapped to start the play.
The National Football League defines all motion and shift penalties as "illegal motion",[1] 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.[2] 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; they are merely starting the play too soon. This is also a five yard penalty.
Both motions and shift were introduced by Amos Alonzo Stagg.[3] The history of college football involves three notable, distinct shifts: