Before they spearheaded the musical phenomenon called “the British Invasion,” John Lennon, Paul McCartney, George Harrison, and Ringo Starr were just four kids from Liverpool. Throughout the 1960s, however, they embodied, as the Beatles, the musical, artistic, social, and spiritual promise of an entire generation. After their stormy breakup in 1970, the Fab Four became four solo artists, at times even appearing on each other’s recordings. In addition to the millions of records each band member has sold on his own since their breakup, more than 40 Beatles compilation albums have been released and continue to sell millions of copies. To this day, more than one billion Beatles recordings have sold, and thousands of books, academic papers, blogs, and websites are dedicated to the group. Despite being the Beatles for only a decade, John, Paul, George, and Ringo together formed the most successful—and arguably the most influential—musical group in history.