Rockabilly is one of the prominent forms of early rock music, with a bebop twelve-beat instead of the eight-beat that become almost universal. The name is a combination of "rock" and "hillbilly." Early rockabilly bands typically generally used electric lead guitar, acoustic rhythm guitar, acoustic (stand-up) bass, and drums. With a rhythm similar to the western swing rhythm that dominated country and western music during the 1950s and generally performed by American Southerners, rockabilly songs appealed to fans of both rock and country and western music. This unifying power of rock music was overlooked by older critics who decried its iconoclastic spirit. Rockabilly exponents included Bill Haley and the Comets and The Everly Brothers.