By the time the Rolling Stones began calling themselves the World's Greatest Rock & Roll Band in the late '60s, they had already staked out an impressive claim on the title. As the self-consciously dangerous alternative to the bouncy Merseybeat of the Beatles in the British Invasion, the Stones pioneered the gritty, hard-driving, blues-based rock & roll that came to define hard rock. They never abandoned blues, but they experimented with pop and psychedelia before landing upon their brawny hard rock signature at the dawn of the 1970s. For the next 50-plus years, they continued to record and perform, and while their records weren't always blockbusters, they were always the most visible band of their era. It is impossible to hear any of the groups that followed them without detecting some sort of influence, whether it was musical or aesthetic.