Sgt. Pepper's Lonely Hearts Club Band (often referred to simply as Sgt. Pepper) is the eighth studio album by the English rock band the Beatles. Released on 26 May 1967,[nb 1] Sgt. Pepper is regarded by musicologists as an early concept album that advanced the roles of sound composition, extended form, psychedelic imagery, record sleeves, and the producer in popular music. The album had an immediate cross-generational impact and was associated with numerous touchstones of the era's youth culture, such as fashion, drugs, mysticism, and a sense of optimism and empowerment. Critics lauded the album for its innovations in songwriting, production and graphic design, for bridging a cultural divide between popular music and high art, and for reflecting the interests of contemporary youth and the counterculture.