A defensive formation in football in which eight of the 11 players on the defense line up on or near the line of scrimmage. The eight-in-the-box defense is primarily used to stop offensive running plays.
The most common formations in football place seven players in the box (an area three to five yards deep and spanning the offensive line), usually a combination of defensive linemen and linebackers. The eighth defensive player in this alignment is usually the strong safety, who comes to the line from his usual position before the ball is snapped. The safety can help against the run, jam wide receivers or tight ends as they come off the line, blitz, or drop back into a coverage shell to help against the pass.
While the eight-in-the-box is not a common defense, teams are often forced to deploy a heavy defensive line when the offensive team has success running the ball. These offenses can take advantage of so many players close to the line of scrimmage, allowing quarterbacks to run play-action to receivers who are more open due to sparse pass coverage. Also, if a running back manages to break through the line, there are fewer defenders to prevent the back from gaining chunk yardage.