This history of rock music is not a history of the charts (which I consider an aberration), but a history of the great ideas introduced by rock musicians over 50 years of relentless innovation, and the history of their greatest albums (regardless of how many copies were sold). It ends up being more focused on alternative rock than on mainstream rock, simply because alternative musicians tend to be more innovative and sincere than mainstream musicians. In a sense, rediscovering alternative rock and giving it its dues is also a way to restore the reputation of rock music among the more sophisticated audiences. Today, rock music is a genre that employs sampling techniques, electronic instruments, digital/computer technology, cacophony, and ethnic sources. The roots of today's rock music lie in the technical innovations brought about in the first half of the 20th century. Therefore, my alternative history of rock music begins much earlier than most books on the origins of rock'n'roll, and covers much more territory than guitar-driven rock'n'roll.