“It’s still a revolutionary thing, to this day, to say, ‘That perfect girl is gone.’”

Billboard is celebrating the 2010s with essays on the 100 songs that we feel most define the decade that was -- the songs that both shaped and reflected the music and culture of the period -- with help telling their stories from some of the artists, behind-the-scenes collaborators and industry insiders involved.

Disney has enjoyed as fruitful of a decade as any entertainment company in the world, thanks in large part to booming properties like Marvel, Pixar, the Star Wars franchise and the Walt Disney Animation Studios.

The crown jewel in the latter’s 2010s run was Frozen, a Hans Christian Andersen adaptation that swelled into the highest-grossing film of 2013. Credit the story of sisters Anna and Elsa -- as well as the kid-friendly comedy of talking snowman Olaf -- but the cinematic phenomenon can also be chalked up to the most beloved Disney original soundtrack in nearly two decades, highlighted by the film’s soaring fulcrum, “Let It Go.”

When Queen Elsa (voiced by Broadway vet Idina Menzel) begins singing “Let It Go,” which was written by the husband-wife musical theater songwriting duo of Robert Lopez and Kristen Anderson-Lopez, she is broken, newly perceived as a monster by her subjects and driven from her home due to her magical powers (“A kingdom of isolation, and it looks like I’m the queen,” she glumly concludes). Yet by the end of the power ballad, Elsa has embraced her new identity, physically constructed her ice castle and emotionally celebrated her inner magic, other perspectives be damned. “Let the storm rage on!” she cries. “The cold never bothered me anyway.”

“We’re not really pop songwriters,” says Lopez, who earned Tonys for the music from Avenue Q and The Book of Mormon prior to working on Frozen, while Anderson-Lopez previously co-wrote the music to Finding Nemo -- The Musical. “All of our songs are really about the story, and ‘Let It Go’ was inspired by the story of Elsa. We always look for these moments where characters make a decision in the story, where they change, and if you took out that song, you wouldn’t be able to understand how.”

“Let It Go” contains one of the most aerodynamic choruses in modern pop music, a defiant bellowing of the titular phrase that makes for perfect sing-along fodder. Lopez, who admits that he recently performed “Let It Go” at a friend’s karaoke birthday party, says of the enormity of Frozen’s musical linchpin, “We realized that this character needed to go from really devastated and small and holding everything in, to letting it all out and releasing her power. Because it told that story, it became a little bit of a stake in the ground for the movie as we developed it, and the thing we always went back to.”

Along with Menzel’s “Let It Go,” Disney released a version of the song with Demi Lovato on vocals, which plays over Frozen’s end credits. Lovato was coming off of multiple top 10 hits on the Billboard Hot 100 chart, yet Menzel’s version of “Let It Go” that plays out in the film was the one that stuck, reaching No. 5 on the chart and becoming the first top 10 hit from a Disney film since “Colors of the Wind” from Pocahontas in 1995. Meanwhile, the Frozen soundtrack topped the Billboard 200 for 13 weeks and became the chart’s most dominant album since Adele’s 2011 album 21, re-establishing Disney as a force on the Billboard charts -- a trend that would continue with the No. 2-peaking soundtrack to 2016 musical Moana, and its own signature Hot 100 hit, the Auli’i Cravalho-sung “How Far I’ll Go.”

Anderson-Lopez credits “Idina’s powerful voice, which is so vulnerable when it’s down low and so uncannily strong the higher she goes, for helping propel “Let It Go” into the cultural lexicon (the song has a whopping 881 million total on-demand streams to date, according to Nielsen Music). She also nods to the stirring animated sequence in the film itself, recalling YouTube sing-along videos in which she noticed kids and adults alike re-enacting Elsa’s physical movements. “When you watch them, they’re all doing the arm choreography! The arm-ography!” she says with a laugh.

“Let It Go” earned Lopez and Anderson-Lopez their first Oscars for best original song; the couple won again four years later for “Remember Me” from Disney’s Coco, and wrote the music for this fall’s Frozen 2 (“The truth is, there’s still a lot for Elsa to sing about,” Anderson-Lopez says of the sequel’s soundtrack). The song has become the essential Disney anthem for a generation whose parents grew up with “A Whole New World,” “Under The Sea” and “Beauty and the Beast,” and Anderson-Lopez is proud of its inspirational message -- particularly for young women.

“It’s still a revolutionary thing, to this day, to say, ‘That perfect girl is gone,’” she says, referring to a key lyric in “Let It Go.” “So much of culture still tries to sort of rein us in, and want us to be quiet and nice and small and pretty. And I do think that ‘Let It Go’ is this moment of like, ‘Screw that!’”