Running out the clock
In American football, each quarter of a game is measured with a 15-minute game clock, or 12-minute clock in many high school football codes and the German Football League. A team in possession of the lead and the ball will attempt to use up as much of the game clock as possible in order to bring the game to an end more quickly, thus denying the opposition another chance on offense.
List of gridiron football rules
The methods of scoring are:Resumption of play following a score is conducted under procedures which vary with the type of score.The game consists of two 30-minute halves, each of which is divided into two 15-minute quarters. The clock counts down from 15:00 in each quarter. Timing rules change when there are three minutes remaining in a half.
A 2-minute interval occurs after the end of each quarter (15 minutes at halftime, except 30 minutes in Grey Cup), and the two teams then change goals.