What is the 4-3 Defense in Football?

The 4-3 defense in football is a defensive alignment strategy consisting of four defensive linemen on the line of scrimmage and three linebackers in the defensive backfield. The 4-3 defense is used primarily as a defense against the run, but can be versatile and guard the pass as well. The four defensive linemen on the line of scrimmage are meant to deter any attempts at running the ball down the middle while the linebackers are to be versatile and defend the run and pass. The other four players on the field are defensive backs, usually two cornerbacks and two safeties.

When the 4-3 defense is used, one or two of the linebackers often begin by lining up at the line of scrimmage to bluff a blitz, then they back up a few yards once the ball is snapped to defend the pass or prepare for the run. Defensive linemen may also back out into coverage, in which the 4-3 defense turns into the 3-4 defense.