Play clock

A play clock, also called a delay-of-game timer, is a countdown clock intended to speed up the pace of the game in gridiron football (American or Canadian). The offensive team must put the ball in play by either snapping the ball during a scrimmage down or kicking the ball during a free kick down before the time expires, or else they will be assessed a 5-yard delay of game (American football) or time count violation (Canadian football; that code's "delay of game" is a different infraction) penalty. If a visible clock is not available or not functioning, game officials on the field use a stopwatch or other similar device to enforce the rule.

In many football games, the play clock is managed by the back judge who is positioned behind the defense and faces the quarterback. When the play clock counts down to 5 seconds remaining, some back judges raise their arm over their head to warn the quarterback, and rotate their arm downward, counting down the final seconds. A penalty flag for delay is thrown afterward.

In the strategy of clock management, a team can slow the pace of a game by taking the maximum amount of time allotted between plays. A team wishing to do so would wait to snap the ball until one second is left on the play clock, or take a timeout. In the latter situation, which usually occurs in the closing minute of the second or fourth quarters before a field goal attempt, the referee will often stand close to the possessing team's sideline, quarterback, or coach to accurately note the maximum time before delay is called was run off, and whistle the clock dead when the timeout gesture is made.