Pink Floyd are an English rock band who initially earned recognition for their psychedelic and space rock music, and later, as they evolved, for their progressive rock music. Pink Floyd are known for philosophical lyrics, sonic experimentation, innovative album cover art, and elaborate live shows. One of rock music's most successful acts, the group have sold over 210 million albums worldwide including 74.5 million albums in the United States alone. Pink Floyd influenced progressive rock artists of the 1970s such as Genesis and Yes, as well as contemporary artists such as Nine Inch Nails and Dream Theater.
Pink Floyd were formed in London in 1965 when Syd Barrett moved down from Cambridge and joined The Tea Set, a group consisting of Regent Street Polytechnic architecture students Nick Mason, Roger Waters, Rick Wright and Bob Klose. The group had moderate mainstream success and were one of the most popular bands in the London underground music scene in the late 1960s as a psychedelic band led by Syd Barrett. However, Barrett's erratic behaviour eventually forced his colleagues to replace him with guitarist and singer David Gilmour. After Barrett's departure, singer and bass player Roger Waters gradually became the dominant and driving force in the group by the late-1970s, until his eventual departure from the group in 1985. The band had always been popular in England, though they did not achieve true worldwide success until the concept albums The Dark Side of the Moon (1973), Wish You Were Here (1975), and Animals (1977), and the rock opera The Wall (1979).
In 1985, Waters declared Pink Floyd "a spent force", but the remaining members, led by Gilmour, continued recording and touring under the name Pink Floyd. Waters sued them for the name and eventually they reached a settlement out of court, under which Gilmour, Mason and Wright would continue as Pink Floyd. They again enjoyed worldwide success with A Momentary Lapse of Reason (1987) and The Division Bell (1994). Waters performed with the band for the first time in 24 years on 2 July 2005 at the London Live 8 concert.