American rock has its roots in 1940s and 1950s rock and roll, rhythm and blues, and country music, and also drew on folk music, jazz, blues, and classical music. American rock music was further influenced by the British Invasion of the American pop charts from 1964 and resulted in the development of psychedelic rock. From the late 1960s and early 1970s, American rock music was highly influential in the development of a number of fusions, including blending with folk music to create folk rock, with blues to create blues rock, with country music to create country rock, roots rock and southern rock and with jazz to create jazz rock, all of which contributed to psychedelic rock. In the 1970s, rock developed a large number of subgenres, such as soft rock, hard rock, heavy metal, glam rock, progressive rock and punk rock. New subgenres that were derived from punk and important in the 1980s included new wave, hardcore punk, post-punk, thrash, and alternative rock. In the 1990s, alternative rock broke through into the mainstream with grunge, and other significant subgenres included indie rock and nu metal. In the 2000s genres that emerged into the mainstream included emo, metalcore and there was a garage rock/post-punk revival. The development of digital technology led to the development of new forms of digital electronic rock. Rock and roll (1950s to early 1960s) Origins The foundations of American rock music are in rock and roll, which originated in the United States in the late 1940s and early 1950s. Its immediate origins lay in a mixing together of various black musical genres of the time, including rhythm and blues and gospel music; in addition to country and western. In 1951, Cleveland disc jockey Alan Freed began playing rhythm and blues music for a multi-racial audience, and is credited with first using the phrase "rock and roll" to describe the music. There is much debate as to what should be considered the first rock and roll record. One contender is "Rocket 88" by Jackie Brenston and his Delta Cats (in fact, Ike Turner and his band The Kings of Rhythm), recorded by Sam Phillips for Sun Records in Memphis in 1951. It has been argued that "That's All Right (Mama)" (1954), Elvis Presley's first major single for Sun Records was the first rock and roll record, but, at the same time, Big Joe Turner's "Shake, Rattle & Roll",