In 1994, when Mariah Carey released "All I Want For Christmas Is You,” there hadn't been a new holiday classic in a decade. And there hasn't been another once since. Mariah’s festive hit is one of the last songs to break into the American Christmas canon. Besides Mariah’s legendary five-octave range, what separates “All I Want for Christmas” from the rest — and why is it the only modern holiday standard? We take a deep dive into the song’s structure to explain its lasting appeal.