The Defensive Back in Football

Defensive backs (DBs) are the four or five defensive football players charged with pass coverage first, and with run support after the pass threat is gone. These players may be cornerbacks or safeties, and they make up the defensive backfield, positioned behind the linebackers or near the sidelines. The backs are unquestionably the fastest and quickest members of the defensive unit, responsible for preventing long pass plays that take place further downfield from the linebackers.

What Defensive Backs Do

Known collectively as the secondary, the defensive backs make up a small team within the team. A fast, versatile, physical secondary is critical to the success of a football team. A defensive back has to communicate well with his fellow backs as they determine the pass strength of the opposing team's formation. DBs have to adjust as an opponent's offense runs motion and formation changes to ensure that they're in the best possible position to stop big pass plays during the game.

Positions

Most defensive formations use two cornerbacks. These backs usually line up on the sides of the defense and are typically charged with covering the offense's receivers. Their goal is to match strides with the receiver, and try to bat away or intercept a pass, or to tackle the receiver as immediately as possible if the ball is caught so he can't run for the end zone.

The secondary also typically features two safeties: a strong safety and a free safety. These defensive backs are positioned between the cornerbacks at the start of the play. The free safety can adjust to the anticipated play, coming forward toward the line of scrimmage when the ball is snapped to cover a short pass, or dropping back to assist the cornerbacks on a long pass. The strong safety, often a bigger and sometimes stronger back, covers the strong side of the field, where the tight end is lined up, and may also come forward to defend against running plays.

Nickel and Dime Defensive Formations

When it's pretty clear that the offense is going to pass the ball--third down and long yardage situations, for example--the defense can add a DB or two to its formation in an attempt to prevent a completed pass. The extra backs must substitute for one of the defensive linemen or linebackers because the team is still limited to 11 defensive men on the field, so someone must come out in order for additional defensive backs can go in. When one DB is added, it's a nickel package. When two backs are added for a total of six players in the secondary, it's called a dime formation.

The Greats

While defensive backs don't always garner attention or awards, some have shined among the sport's best players. San Francisco safety Ronnie Lott and Dallas cornerback Deion Sanders are examples of standout defensive backs, as is Charles Woodson, who played safety and cornerback for Oakland and Green Bay.