Play clock

A play clock, also called a delay-of-game timer, is a timer designed to increase the pace – and subsequently, the scoring – in American football and Canadian football. 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 (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 will use a stopwatch or other similar device to enforce the rule.

In Canadian football, the offensive team must run a play within 20 seconds of the referee whistling the play in; in amateur American football, teams have 25 seconds from the time the ball is declared ready for play. In the NFL teams have 40 seconds timed from the end of the previous down, or 25 seconds after the ball is declared ready for play after certain administrative stoppages and game delays. Before 2008, in college football, the play clock was 25 seconds after the ball was set, but the clock was not stopped for the ball to be set unless the previous play resulted in a stoppage of the clock. Now, the same intervals as the NFL are used, with minor differences for the final two minutes of each half. Various professional leagues have used their own standards; the XFL, for instance, used a 35-second play clock to encourage faster play.