Rockabilly was a wild, hepped-up meeting between country & western music and early rhythm & blues. It was one of the very first forms of rock & roll, and it was the first one performed predominantly by white musicians (almost all of whom came from the South). Rockabilly was played with spare instrumentation: a twangy electric guitar and an acoustic stand-up bass whose strings were snapped percussively in a technique dubbed "slap-back" (which sometimes made drums unnecessary). Rockabilly had a thumping, jumping beat that easily made it the most propulsive, visceral, and implicitly sexual style of "white" American music up to that point. Essentially, it made rock & roll accessible to white audiences, thus touching off a cultural revolution the effects of which are still being felt.