The Beatles follows the extraordinary development of four self-taught musicians from Liverpool who revolutionized the world of popular music and created a treasury of songs astonishing for their variety and innovation. From the time of 'Love Me Do', their 1962 debut single, until their breakup in 1970, they consistently explored new composition territory with each new recording. By the time of Sgt.

Pepper's Lonely Hearts Club Band in 1967, they were writing songs steeped in sophisticated imagery, and had added harpsichords, sitars, backward-running tapes and orchestral instruments to their original guitar, bass and drum format. Well before Sgt. Pepper, though, the Beatles were enthusiastically embraced by composers and critics of classical training, who saw in their early work an originality that transcended both the ambitions and traditional limitations of pop music.

.

Discussion of the Beatles' music is expanded here by a consideration not only of the group's commercially released disks but also of rare working tapes which illuminate the compositional process and reveal how some of their milestone recordings took shape in the studio.

This study is presented within the context of the group's broader evolution - from the skiffle and dance band, via its flirtations with folk, country and electronic music, through to its final flowering in the extended suite that closes Abbey Road - and set against the backdrop of the popular culture explosion of the 1960s.