Pop music has been the soundtrack to our tumultuous times, an inescapable medley of ever-shifting beats and melodies, snappy hooks and pithy lyrics encapsulating and illuminating life on Earth. It took flight with the invention of the radio and record player in the early 20th century, and particularly since the youth-quake explosion of rock 'n' roll coincided with the proliferation of mass communication technology in the 1950s. Music is everywhere, deeply embedded in our everyday lives. We are a people of song, living on a jukebox planet. And these are my candidates for the 50 greatest songs of our times.