What it is

An audible is a change of play called by the quarterback at the line of scrimmage after he reads the defense.

In a game

He uses a short code word or number that his teammates already know. Crowd noise can make audibles harder to hear.

More detail

Quarterbacks use signals and dummy calls to hide the real play. A common use is checking from a pass to a run when the defense drops many defenders into coverage, or the other way when the defense stacks the box. Some plays are called with two options so the quarterback can choose without a signal.

Animated diagram

1. The offense lines up and the quarterback studies the defense before the snap.
2. He sees a defense that will not work for the play call, so he shouts a code or uses hand signals to change it.
3. The running back and the defense both adjust. Then the ball is snapped and the new play begins.