In American football, rushing has two different meanings.
Offense
The first is an action taken by the offensive team that means to advance the ball by running, as opposed to passing. A run is technically any play that does not involve a forward pass. It is usually done by the running back, after a hand-off from the quarterback, although quarterbacks and receivers can also run. The quarterback will usually run when a passing play has broken down, because there is no receiver open and the field has opened up. A team with an athletic quarterback may regularly call designed run plays for the quarterback, although, because of the risk of injury, this is rare. A wide receiver can run on an end-around, reverse, or on a screen pass. On the screen pass the quarterback will usually throw overarm, and whether it is a run or pass will depend on whether the pass goes forward or backwards. A wide receiver screen is usually intended to be a pass as if the wideout drops it, it is an incompletion rather than a fumble.
Defense
The other is an action taken by the defensive team that means to run towards the quarterback or kicker across the line of scrimmage. The purpose is tackling, hurrying or flushing the quarterback, or blocking or disrupting a kick. In both college and professional football, getting a strong pass rush is an important skill, as an average quarterback will often be able to be productive, even against a strong secondary, if he has lots of time to pass the ball. Teams will improve their pass rush by blitzing, which sends additional men at the quarterback. The rules on tackling a quarterback are fairly protective, and very protective in regards of the kicker. This has resulted in most teams sending few men at the kicker, as the risk of drawing a penalty is too great to justify the low chance of blocking a kick.
