A statistic credited to a defensive players when physical contact with a quarterback causes him to be ruled down by contact behind the line of scrimmage. In order for a sack to be recorded, it must be obvious that the quarterback either intends to throw a forward pass, or is still in the "pocket" without a clear objective for the play.
More about NFL Sack and Sack Yard Leaders
Sacks didn't become an official NFL statistic until the 1982 season. Michael Strahan holds the record for the most sacks in a single season with 22.5.
As of 2013, the player who ends the season with the most sacks is given the Deacon Jones Award.