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
A standard football game consists of four 15-minute quarters (12-minute quarters in high-school football and often shorter at lower levels, usually one minute per grade [e.g. 9-minute quarters for freshman games]), with a 12-minute half-time intermission (30 minutes in Super Bowl) after the second quarter in the NFL (college halftimes are 20 minutes; in high school the interval is 15 or 20 minutes; 10 minutes for lower grades). The clock stops after certain plays; therefore, a game can last considerably longer (often more than three hours in real time), and if a game is broadcast on television, TV timeouts are taken at certain intervals of the game to broadcast commercials outside of game action. If an NFL game is tied after four quarters, the teams play an additional period, timed like the fourth quarter, lasting up to 10 minutes. There is a coin toss in the NFL just like the beginning of the game. If the receiving team scores a touchdown during the possession, they win. If they kick a field goal, then the other team gets a possession. If they score a touchdown, they win. If they tie the score by kicking a field goal, then the next team that scores wins. If the team with the first possession turns the ball over without scoring any points, then the first team to score, wins. If the defense scores a touchdown through an interception or fumble recovery, or they get a safety, then they win. In a regular-season NFL game, if no one scores in the overtime, the game ends tied. In an NFL playoff game, multiple 15-minute overtime periods are played, as needed, to determine a winner. These periods are timed as if a game had started over. In the extremely rare case a game would go as far as a third OT—which has never happened in the NFL—there would be no "halftime intermission"; play would resume with a kickoff similar to a normal third quarter.