Pink Floyd are an English rock band that earned recognition for their psychedelic rock music, and, as they evolved, for their avant-garde progressive rock music. Pink Floyd were known for philosophical lyrics, sonic experimentation, innovative cover art, and elaborate live shows. One of rock music's most successful and influential acts, the group has sold over 250 million albums worldwide, and an estimated 73.5 million albums in the United States alone.
Pink Floyd had moderate success in the late 1960s as a psychedelic band led by the late Syd Barrett, however, Barrett's erratic behaviour forced his colleagues to eventually replace him with guitarist and singer David Gilmour. After Barrett's departure, singer and bass player Roger Waters gradually became the band's leader and main songwriter. Under Waters, the band recorded several concept albums, achieving worldwide success with The Dark Side of the Moon (1973), Wish You Were Here (1975), Animals (1977), and The Wall (1979). In 1985, Waters declared Pink Floyd defunct, but the remaining members, led by Gilmour, continued recording and touring under the name, enjoying commercial success and eventually reaching a settlement with Waters.