What it is

A box coverage is a split-safety coverage in which four defenders work together against three receivers on one side of the formation, usually the side with three receivers.

In a game

The cornerback, the apex, the hook and the safety share the #1, #2 and #3 receivers, and together they form a box on the field. The extra defender is useful against three receivers on one side, or against a running back who lines up wide and becomes the third receiver on that side.

More detail

Because the box coverage takes care of the three-receiver side on its own, the other side of the field can play a different coverage, such as a triangle coverage. That is how a defense can have one answer for the strong side and another for the weak side. The hook is the defender who is added to the triangle.

The diagram

1. Four defenders work together: the cornerback, the apex, the hook and the safety.
2. They cover three receivers, #1, #2 and #3.
3. The other side of the field can play a different coverage.