What makes a song last? The history of popular music tells us that many masterpieces of songcraft—and even the most world-conquering smashes—are quickly forgotten. Meanwhile, many earworms burrow deep into the collective consciousness, where they take root, whether we like it or not. Who could have predicted that “Don’t Stop Believin’ ”—which was, upon its release in 1981, a flop from a critically derided band—would become the 20th century’s best-selling digital download? Or that it would be a “novelty” dance single, of all song varieties, that would become Billboard’s pick for the greatest single of all time?