In football, the pocket is the area behind the offensive line where the quarterback stands after receiving the ball. The pocket is about seven yards wide and five yards long. Offensive linemen form the pocket by dropping back to defend the quarterback from oncoming defenders. The pocket is often described as a wall around the quarterback.
While in the pocket, the quarterback usually stands looking for a receiver to pass the ball to. If there is no receiver open and the defense is closing in, the quarterback can scramble from the pocket and attempt to run for yards, or pass the ball while outside the pocket. The pocket's main goal is to give the quarterback a moment of extra time to think about his next time.
If defenders get close to the quarterback while in the pocket and the quarterback intentionally throws the ball into the ground or out of bounds before the first down line in an attempt to not lose yardage on a sack, an intentional grounding penalty is called. However, if the quarterback throws the ball away while outside of the pocket, even if being chased by defenders, the penalty is not called.