<P> Rock and roll emerged as a defined musical style in the United States in the early to mid-1950s . It derived most directly from the rhythm and blues music of the 1940s, which itself developed from earlier blues, boogie woogie, jazz and swing music, and was also influenced by gospel, country and western, and traditional folk music . Rock and roll in turn provided the main basis for the music that, since the mid-1960s, has been generally known simply as rock music . </P> <P> The phrase rocking and rolling originally described the movement of a ship on the ocean, but it was used by the early twentieth century, both to describe a spiritual fervor and as a sexual analogy . Various gospel, blues and swing recordings used the phrase before it became used more frequently--but still intermittently--in the late 1930s and 1940s, principally on recordings and in reviews of what became known as rhythm and blues music aimed at a black audience . In 1951, Cleveland - based disc jockey Alan Freed began playing this music style while popularizing the term rock and roll to describe it . </P>

Where did the term rock and roll originate