Snap (gridiron football)

Because of the vulnerability of a player in such a position, the National Collegiate Athletic Association (NCAA) and the National Federation of State High School Associations ("Fed") have adopted rules providing that if a player is positioned at least seven yards behind the neutral zone to receive a snap, opponents are not to deliberately contact the snapper until one second after the snap (NCAA), or until the snapper has a chance to react (Fed).

However, in professional football it is common for a center to be able to practice a single "shotgun" formation thrown snap enough to keep his head up and toss it blindly.

being the final words spoken by the quarterback after calling the play but before the huddle breaks and the players go to the line of scrimmage.

The defensive players want to predict the snap, and build up speed such that they cross the line of scrimmage exactly as the play begins, to increase their chances of getting a tackle for a loss or a sack.

Successfully simulating the count would cause members of the offensive team to act too early ruining co-ordination of the play and inviting penalties.

As the rules of rugby's scrimmage were written when the game came to North America, they had a significant flaw which was corrected by custom elsewhere, but by the invention of the snap in American football.

[3] The rule adopted by a committee for American football in 1880 first provided for the uncontested right of one side to play the ball by foot (in any direction) for a scrimmage.

The game design rationale for requiring the snap to be a quick and continuous motion to the backfield is to eliminate the need for rules provisions for a live ball in scrimmage.

In American and Canadian football, the ball as it is put in play is only held in the line (by the center) for a fraction of a second.

The uncontested possession also, as Walter Camp pointed out, allows for better offensive and defensive planning by the side entitled to snap the ball and their opposition, respectively.