What all Christmas movies have in common

’Tis the season for sitting in front of the cozy glow of a Christmas movie. Don’t you just love the snow, the twinkling tree lights, and, of course, the charming sounds of festive music?

But not all Yuletide melodies are created equal.

In a 2015 analysis, FiveThirtyEight found that nine out of the top 10 most featured Christmas songs on movie soundtracks were in the public domain. In other words, Christmas movies are full of the classic songs we know and love — that also happen to be free from copyright and expensive licensing fees.

The reason why public domain Christmas songs are so popular may be obvious: Lower-budget films, like the ones our moms have grown to love from the Hallmark channel, can’t always afford to pay for newer, popular songs. But older public domain Christmas songs also hold a unique charm. Their repeated presence over the years has woven them into the very fabric of the holiday season, creating a sense of shared joy and nostalgia.

And composers like Russ Howard III, who we interviewed for this video, know this. He explains that musicians will often use public domain Christmas songs as a starting point for creating original compositions. Taking cues from classics like “Deck the Halls,” they craft new pieces that fit seamlessly into the emotional beats of a scene, while still having a festive flair.

For a closer look at the artistry behind your favorite holiday movie’s tunes, check out Vox Videos’ latest.