Block (American football)

In American football, blocking or interference (or running interference) involves legal movements in which one player obstructs another player's path with their body. The purpose of blocking is to prevent defensive players from tackling the ball carrier, or to protect a quarterback who is attempting to pass or hand off the ball. Offensive linemen and fullbacks tend to do the most blocking, although wide receivers are often asked to help block on running plays and halfbacks may be asked to help block on passing plays, while tight ends perform pass blocking and run blocking if they are not running routes to receive passes.

Essentially, blocking is pushing, with certain restrictions; in blocking one may not grasp another player or do any sort of pulling, and the hands must not extend beyond the line of each armpit; otherwise a holding penalty will be assessed. Blocking is also not permitted beyond five yards from the line of scrimmage until the quarterback has handed off the ball to a runner or a receiver has touched the ball after it has been passed.

Outside sports, "running interference" is a metaphor that refers to a person's helping someone in the performance of a task without directly assisting in the task. Often this is done by attracting attention to oneself (so as to deflect attention from the other person) or throwing oneself into harm's way.

Zone blocking is a technique that is a simple and effective scheme for creating lanes for running plays. In a zone blocking scheme, fleet-footedness and athletic ability trump size as desirable qualities in offensive linemen. Coordination and technique matter more than muscle in implementing a successful scheme because defensive linemen are often double-teamed at the point of attack. In this blocking scheme, which takes much from the Veer blocking system, creating movement on the defensive line is more important than opening a specific hole in the defense.

One of the simplest reasons many teams have incorporated zone blocking in their offenses is that zone blocking rules do not change based on the defensive front. In a "man block" system, blockers are paired with defenders according to certain rules to create a running lane. If the defensive front changes, or if the defense stunts or blitzes, the blocking rules may change. This requires learning multiple rules for the same play. Zone blocking uses very consistent rules that do not change according to the defensive front.

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