Elvis Presley and Karlheinz Stockhausen. The Beatles and Andy Warhol. Terry Riley and Ken Kesey. What all these artists have in common is that loops have played a significant role in their work. The short sequences of sounds or images repeated using recording media have proved to be an astonishingly flexible, versatile and momentous aesthetic method in post-World War II art and music. Today, loops must be counted among the most important creative tools of postmodern art and music. Yet until now they have been largely overlooked as an aesthetic phenomenon. Now, for the first time, this book tells a secret story of the 20th century: how a formerly inconspicuous basic function of all modern media technology gave rise to complete artistic oeuvres, musical styles such as minimal music, hip hop and techno, and, most recently, entire scenes and subcultures that would have been unthinkable without loops.