In
American football and
Canadian football, a
sack occurs when the
quarterback (or another offensive player acting as a passer) is
tackled behind the
line of scrimmage before he can throw a
forward pass, when the quarterback is tackled behind the line of scrimmage in the "
pocket" and his intent is unclear, or when a passer runs out of bounds behind the line of scrimmage due to defensive pressure. This often occurs if the opposing team's
defensive line,
linebackers or
defensive backs are able to apply
pass pressure to quickly get past
blocking players of the
offensive team (the quarterback's protection), or if the quarterback is unable to find a back to hand the ball off to or an available eligible receiver (including
wide receivers,
running backs and
tight ends) to catch the ball, allowing the defense a longer opportunity to tackle the quarterback. A quarterback that is pressured but avoids a sack can still be adversely affected by being forced to
hurry.