Barrett became the driving force of the group, writing their two hit singles Arnold Layne and See Emily Play, and most of the songs on their first album, The Piper at the Gates of Dawn. Piper has been called the greatest British psychedelic album with the possible exception of the Beatles Sgt. Pepper's. While touring the US, problems with Barrett started to surface. Mental problems marked by a fragile hold on reality combined with frequent LSD use, had taken a heavy toll on Syd. On stage he would either stop playing completely or play notes that had nothing to do with what the group was playing. In time, the group realized something had to be done. At first they hired Dave Gilmour, a friend of Barrett, to play on stage while Barrett continued to write and work in the studio, but Barrett's continuing spiral ended all hopes of his staying with the group.
Pink Floyd's next album, Wish You Were Here, 1975, a complex concept album that in part paid tribute to Barrett, topped the charts in the U.K. as well as the U.S. Waters' seething perspective of modern society continued to be the theme of the group's next two albums, Animals, 1977, and The Wall, 1979. Long known for their innovative stage presentations, their live stage presentation of The Wall included the brick by brick construction of a wall between the group and the audience as they played the album in its entirety. Surprisingly, a single from the album, Another Brick in the Wall, Part II, became a top ten hit.
After a legal skirmish with Waters over who held the rights to the group's name, Gilmour and Mason continued as Pink Floyd, joined later by Wright. The three produced two more albums — A Momentary Lapse of Reason (1987) and The Division Bell (1994) — and continued to tour until 1995. In 2005, after nearly two decades of animosity, Gilmour, Wright, Mason and Waters reunited as part of the global awareness event Live 8; Gilmour and Waters stated they had no further plans to reunite the band. Barrett died in 2006, and Wright in 2008. The last Pink Floyd studio album, The Endless River (2014), was recorded without Waters and based almost entirely on unreleased material from The Division Bell recording sessions.
Pink Floyd were inducted into the American Rock and Roll Hall of Fame in 1996 and the UK Music Hall of Fame in 2005. By 2013, they had sold more than 250 million records worldwide.