In football, a sack is when a defensive player tackles the quarterback behind the line of scrimmage when the quarterback is intending to throw the football. A sack is a major blow to the offense as it pushes them backwards in field position for the next down.
A sack is when a defensive player, usually a linebacker or a player on the defensive line, tackles the quarterback in the backfield before they could throw the ball or get past the line of scrimmage. It occurs exactly like a normal tackle, simply involving the quarterback rather than any other player. A sack most often results in a loss of yards on the play and the next down will begin after the sack. The record for the most sacks in an NFL season belongs to Michael Strahan in 2001 when he recorded 22.5 sacks. Sacks can also be .5 (half-sacks) if multiple players sack the quarterback at the same time.
A sack is also recorded if the quarterback runs out of bounds before reaching the line of scrimmage. The sack is credited to the nearest defender. In the NFL, a sack removes total rushing yards from a teams total in the stats but not from the individual quarterback. In the NCAA, a sack removes rushing yards from a teams total in stats and the individual player who is tackled, including the quarterback during a sack.
For a tackle to be called a sack, the player being tackled must be the quarterback who has the intent to pass the ball and the tackle must be made at or behind the line of scrimmage. If the quarterback is intending to run, the stat is not called a sack. If the quarterback has no clear intent, statisticians take into account offensive formation to determine what kind of play was being run. If multiple players sack the quarterback at the same time, they are awarded 1/2 sacks (0.5 in statbooks). If there are more than two players that sack the quarterback at the same time, they are all still awarded 1/2 sack.