What it is

The snap count is the signal that tells the offense when the ball will be snapped. The quarterback calls out words and numbers, such as “set, hut, hut.”

In a game

Everyone on the offense knows the count, so they move together. A defender does not know it, so he has to react.

More detail

A hard count uses a different rhythm to try to make a defender jump offside. Quarterbacks use it, especially at home, where the crowd is quiet and the noise does not drown out the call.