In American football, "West Coast Offense" ("WCO") is a common term for an offense that places a greater emphasis on passing than on running. There are two similar but distinct offensive-strategic-systems of play which are commonly referred to as "West Coast Offenses": (A) the Air Coryell system popularized by Don Coryell; or (B) more commonly the offensive system popularized by Bill Walsh characterized by short, horizontal passing routes in lieu of running plays to "stretch out" defenses, opening up the potential for long runs or long passes.