A gap (gap lettering)

Football names the spaces between blockers with letters, working from the ball out: the A gap sits between center and guard, the B gap between guard and tackle, the C gap between tackle and tight end, and the D gap outside the tight end. Every run fit, blitz, and technique number hangs off this system — a defense that's 'gap sound' has one defender responsible for every letter, and an A-gap blitz is coming right up the middle. Learn the letters and the whole chess match up front starts making sense: linemen aren't blocking men so much as fighting over gaps.

Defined by Coach Jay Freeman — 34 years coaching the offensive and defensive line.

Related trench terms

1-gapD-Line

A defensive technique where the lineman attacks one specific gap — more aggressive and more upfield.

2-gapD-Line

A defensive technique where the lineman is responsible for both gaps on either side of the blocker he lines up over.

3-techniqueD-Line

A defensive tackle aligned on the guard's outside shoulder — the B-gap penetrator spot.

Inside zoneO-Line

A run scheme where all blockers step playside, working combo blocks up to the linebackers.

DuoO-Line

A downhill run built on double teams with no puller — 'power without the pull.'

Go deeper

• Coach Jay’s lineman training library — the technique behind the term →
• Back to the full Trench Dictionary →
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