also: reach · hook block
Blocking a defender who is aligned outside you, getting your helmet across his outside shoulder. The block that defines zone running, and the one most likely to fail.
A reach block asks a lineman to block a defender who is aligned playside of him, which means winning a race to a point the defender starts nearer to. The finish position is the definition: helmet across the defender's outside shoulder, so the lineman ends up between the defender and the sideline and the runner can get outside.
It is the defining block of outside and wide zone. It is the reason those schemes live or die on the athleticism of the line rather than on its size. A reach block that is only half-won still has value, because it turns the defender's shoulders and lets the back cut behind it, which is the built-in fallback zone schemes are designed around.
hook blockdown block, scoop block, base blockReach and hook are used for the same block by most coaches. Where a staff separates them, hook usually names the successful outcome and reach names the attempt, which is a distinction worth knowing exists rather than one worth arguing about.
The hardest block on this list to execute at youth level, because it is the one that cannot be solved with effort or angle. A line that cannot reach cannot run outside zone, which is a real reason to pick a gap scheme instead rather than a coaching failure to fix.