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.
American football rules
Each team receives three timeouts per half (if the game goes to overtime, each team receives additional timeouts), making for a total of six timeouts per team in a regulation game. Unused timeouts may not carry over to the second half or overtime. In professional football, a team must have at least one remaining timeout to challenge an official's call.