Even the phrase "rock 'n' roll" itself"broke up." It came to refer to the music of the 1950s and the guitar-based hard rock of sixties bands like the Rolling Stones. It was replaced in popular consciousness with the term "rock." The catchall referred to any kind of up-tempo or mid tempo music by or for young people. In the 1970s, "rock" could be soft or loud, smart or dumb, pretentious or natural, fast or slow, with guitars or synthesizers, contrived or spontaneous. From this point on, for simplicity and sanity, "rock" and "rock 'n' roll" are used interchangeably.