When at the line of scrimmage, many teams will shift prior to the snap. This is usually a wide receiver, running back, or tight end. Once the player or players have completed shifting, the quarterback must pause for at least one second before having the center snap the ball. If the quarterback fails to pause, a 5-yard penalty will be assessed.
This penalty was implemented to prevent quarterbacks from gaining an advantage from shifting players in order to distract the opponent. A distracted opponent may jump off-sides or commit a neutral zone infraction, both of which are penalties on the defense. Instituting the pause places both teams on equal footing in the moments immediately preceding the snap. Quarterbacks must also pause for one second after the huddle, but this is almost never a problem in the modern NFL, as teams take at least a few seconds to setup after the huddle. Even in the case of a no-huddle offense, teams will take at least one second to prepare for the snap.