So which artist was the first to sell a million ringtones? Who had the most-downloaded song last year? And what obscure bands have risen to fame thanks to the popularity of the Guitar Hero video game series?

You can find the answers to those questions and others in ContentNext’s “10 Songs That Rocked the Digital Music World,” which details the rise of digital music through actual tunes. With the emergence of the iPod, YouTube and the “mashup,” music is being created, marketed and consumed in new ways. Our list, the result of extensive research, singles out artists like T.I., Danger Mouse and Jet, who have played a significant role in those chapters, and tells the backstory behind these key songs.