A term in football that describes a change in formation by one or more players prior to the ball being snapped.
There are multiple strategies behind offenses choosing to shift (change) a formation. A shift can occur when the offense is responding to a particular defensive formation, after an audible has been called and the play is changed, or just to confuse the opposing defense and force individual players to react quickly.
A shift is only valid if all players involved in the shift reset their positions at least one second before the ball is snapped. If they fail to do so, a penalty will be called, resulting in a loss of five yards.
It is important to make a distinction between shifts and motions, as a shift occurs before the snap, while a motion occurs as the ball is being snapped.