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.
Delay of game
In American football, an offensive team is penalized five yards for delay of game if it fails to put the ball in play by either snap or free kick before the play clock expires. This time limit varies by league, and is often 25 seconds from the time the referee signals the ball ready for play. In the National Football League, it can also be 40 seconds from the end of the previous down, depending on the circumstances at the time. Also, the defensive team can be given the same penalty if, after a play has ended, they fail to quickly yield the ball to officials, prevent a player on the offense from getting up, or kick the ball.