Terminology

A defensive lineman aligned head-up on the center.

A defensive lineman aligned on the outside shoulder of the center (in the A gap).

A defensive lineman aligned head-up on the guard.

A defensive lineman aligned on the inside shoulder of the guard.

A defensive lineman aligned on the outside shoulder of a guard.

A defensive lineman aligned head-up on the tackle.

A defensive lineman aligned on the inside shoulder of the tackle.

A defensive lineman aligned on the outside shoulder of the tackle.

A defender aligned head-up on the tight end.

A defender aligned on the inside shoulder of the tight end.

A defender aligned outside the tight end, commonly a contain/edge alignment.

The space on either side of the center, between the center and the guard.

Where you line up before the snap.

The space between the guard and the tackle. Coaches usually identify it as the left or right B gap based on the offensive front.

The side of the formation away from the play call. Often the cutback side on runs.

A one-on-one block on the defender aligned across from the blocker.

The space between the tackle and the tight end (or outside the tackle if no tight end).

One blocker on a combo leaves the down lineman and works up to block a linebacker.

Two blockers work together on a down lineman before one climbs to a linebacker.

Keeping the ball inside your outside shoulder — the QB or ball carrier cannot get outside of you.

A zone defender responsible for the curl area first and the flat second (or vice versa depending on the read).

The space outside the tight end. Commonly the edge/contain gap.

One of three deep zones split across the width of the field, commonly in Cover 3.

Two blockers stay on one defender to move him vertically off the line of scrimmage.

An angle block on a defender aligned inside of the blocker.

The player responsible for turning the ball back inside on outside runs.

The side of the formation the play is designed to attack.

Every defender fitting the gap he is assigned, so no run lane opens up.

Aligned directly in front of an opponent, not shaded inside or outside.

An intermediate zone inside the numbers, roughly 10-14 yards deep.

Positioning so your body is aligned to the inside of the receiver or ball carrier.

The player or offensive lineman you watch to identify run or pass and direction.

A block that widens an edge defender outward, opening a lane inside of him.

A spot on the field you must reach or protect — a hash, numbers, gap, or zone drop point.

A defender is responsible for a specific receiver anywhere he goes.

Positioning so your body is aligned to the outside of the receiver or ball carrier.

A lineman leaves his initial spot and runs behind the line to lead-block on another gap.

A block designed to get the blocker's helmet across the playside shoulder of a defender aligned outside.

The exact job you must do on a play, regardless of what teammates do.

The specific gap and body position a defender takes on a given run scheme.

The vertical lane between the hash and the numbers.

Wrong-arming a blocker so the ball is forced to bounce outside to help.

Playing from depth downward on a receiver or route, keeping everything in front of you.

The moment your key confirms the play — the cue to attack or drop.

A defender is responsible for an area of the field and the receivers who enter it.