Songfacts®:

• Pentatonix are an a cappella group comprising Scott Hoying, Kirstie Maldonado, Mitch Grassi, Avi Kaplan and Kevin Olusola. The quintet released a video in late 2013, in which they covered The Harry Simeone Chorale's holiday classic to the background of Los Angeles as a gift for their three million followers. The clip began with 6.4 million US Streams in its first week, resulting in it debuting at #13 on the Hot 100, which was coincidentally the peak position of The Harry Simeone Chorale's famous rendition of the song.
  
  The song achieved a high chart placing as a result of a change in Billboard's methodology in February 2013, when YouTube views and other streams became a factor in tabulating the Hot 100. Baauer's chart-topping single, "Harlem Shake" was the first song to benefit from the new policy.
• Asked by Billboard magazine what the impetus was for recording the song, the quintet replied: "We'd been wanting to arrange the song for a while, but could never really figure out a direction. We decided to just try it out, and we were incredibly happy with the way it turned out!"