Between the start of 2017 and its close, the K-pop world has notably fluctuated: prominent acts have disbanded or lost members, BTS has made history multiple times on Billboard charts and in the American music market, new sonic trends have risen to prominence and new artists found their place in the spotlight while others have faded away.

But while K-pop in 2017 has been defined by change, one thing that’s always stable about the Korean music industry is that it always offers new and exciting songs. As in previous years, Billboard’s team took a look back at the best songs of 2017. Reflecting both personal tastes and chart achievements, this is our take on the best Korean music of the year -- featuring tunes from some of the most popular acts, like Wanna One, IU and BTS, as well as some surprises from less-established artists.

20. EXO, “Ko Ko Bop” (The War)

This electro-reggae track was the perfect blend of propulsive and breezy sound when it came out in July. Based around a swaying chorus that draws on the children’s rhyme “Down Down Baby,” “Ko Ko Bop” veers this way and that, laying heavy-handed raps and EDM breakdowns beside mellow verses overflowing with ambient harmonizing guided by staccatoed percussion and squaling synths. Dynamic in its creative styling, EXO’s first single of the year added a new color to the boy band’s sound while still maintaining their dedication to dance-focused pop music, and that’s a good look for this K-pop powerhouse. -- TAMAR HERMAN

19. Dreamcatcher, “Chase Me” (Nightmare)

Horror thrives on distorting the things that are supposed to feel safe -- evil is that much more chilling when it takes the form of dolls, children and music boxes. That’s part of the reason why Dreamcatcher is such a compelling girl group. K-pop has never before seen an act commit so fully to a spooky concept. Rapidly thumping kick drums rev this banger into gear with the help of some six-string shredding. This fusion of thrash metal and K-pop adds a dark twist to pop song structures, making it the kind of jam you’ll want to go bump in the night. -- CAITLIN KELLEY

18. Akdong Musician, “Dinosaur” (Summer Episode)

The beauty of Akdong Musician’s music is always that the pair put a part of themselves into it, and this ambient take on EDM is no different. Singing about childhood fears and growing up to roar back at the titular nightmare, the brother-sister duo builds the song from gentle acoustic strings into a soaring track littered with twinkling electronica blips as they let loose with their vocal performance. Invigorating in its nostalgic approach to dance music, “Dinosaur” showcases a new side to the Lee siblings in a way that still retains the wholesome AKMU charm. -- T.H.

17. NCT 127, “Cherry Bomb” (Cherry Bomb)

NCT 127 is only a rookie group, but they’d have you believe they’re “the biggest hit on this stage” with this menacing statement piece. The artful cacophony of sounds is positioned slightly off-center to give the song an eerie vibe. The Doppler effect whooshes back and forth in the background while pitched up and warped synths swirl in the distance. SM Entertainment proves that popularity doesn’t detract from the experimentalism at the core of the label, which is practically built into the framework of NCT as an ever-shifting mass of subunits. -- C.K.

16. Suran (feat. Dean), "1+1=0" (Walkin’)

If you add Suran and Dean together, you get the opposite of zero. The title is a play on words, as the Korean word for “one” also means “work.” The lyrics, penned by Dean, dig into how hyper-productivity leaves personal lives empty, which is poignant in a society that is overrun by an overloaded workforce. "1+1=0" at once feels minimalist and heavily textured. The assemblage of the laid-back funk riff, flute accents and chorus of vocal samples leave enough room for Suran’s airy yet soulful voice to be complemented by Dean’s R&B inflections. -- C.K.

15. Pristin, “Wee Woo” (Hi! Pristin)

From the moment its irresistible disco-guitar lick opened the track, one of 2017's most impressive rookie acts were confirmed onto the K-pop scene. The ladies of Pristin sang, rapped and bu bu-ed their way to craft one of the year's most effortlessly satisfying songs, only enhanced by the fact the group had a major hand in writing their debut single -- a notable rarity in the industry. -- JEFF BENJAMIN

14. Girls’ Generation, “All Night” (Holiday Night)

2017 marked the 10-year anniversary of these K-pop icons and they did not disappoint with this slick single. The women bring the glossy pop they've long been famous for, before the track pulls a 180 on the chorus with a house-inspired beat, making "All Night" as appropriate for a vogue-off as it is for a K-pop concert. A decade on the scene and Girls' Generation is proving to still have a few new sonic tricks up their sleeves. -- J.B.

13. Loco feat. Dean, “Too Much” (Bleached)

“Too Much” is a lyrical game of cat-and-mouse with one’s own emotions, as Loco and Dean veer between restraint and desire upon seeing an overwhelmingly beautiful woman. The laidback tempo makes the repetition of the phrase “too much” feel like lyrical dissonance, while the hazy trap-n-B beat is offset by twinkling xylophones and jazzy horns. The track, produced by Gray, is the brainchild of artists who specialize in smoothness. -- C.K.

12. Loona / Odd Eye Circle, “Sweet Crazy Love” (Mix & Match reissue)

Loona is already disrupting K-pop norms, and they haven’t even formally debuted yet. Orchestral meets electronic on a propulsive beat set to galloping percussion. The trio makes saccharine sound eccentric as their sweet soprano ranges twist and turn on R&B-style vocal runs. It’s like a fairytale how this relatively small group’s unique pre-debut promotions have made them a cult favorite among international K-pop fans. Soon enough, this mysterious girl group will be making Loonatics of us all. -- C.K.

11. Sons of People, “Never” (Produce 101 - 35 Boys 5 Concepts)

One of the most robust Korean releases of the year, “Never” came out of the latest season of Produce 101 as a one-off performance, but it endures thanks to its immense popularity. With layered vocals, powerful raps, and propulsive drops flowing into a blend of subtle, melodious instrumental elements and frenzied synths, the deep house track proved to be one of the best sonic moments of K-pop in 2017. Sons of People may not have lasted longer than an episode or two -- though all but one member made it into the show's final lineup to go on and become Wanna One -- but they'll certainly live on with this hit. -- T.H.

10. NU’EST W, “Where You At” (W, Here)

K-pop's Cinderella story truly had its happy ending when the boys of NU'EST unleashed one of the best tracks of the year ... and got their due recognition for it. "Where You At" capitalizes on the band's long-running embrace of experimental, electronic elements served with their penchant for emotional deliveries. But the song also had a deeper meaning, with its heavy emphasis on zippy synthesizers seemingly taking the place of NU'EST vocalist Minhyun, who the "W" in NU-EST W stands for, as the band waits for his return during his year promoting with Wanna One. -- J.B.

9. Subin, “Circle’s Dream” (Circle’s Dream)

“Circle’s Dream” is what happens when coffee house indie meets sleek K-pop production, with a quirky sound palette that’s sparse and playful in its staccato percussion and plinking synths. The sleekly layered production has Subin of Dal Shabet being her own back up vocalist as she croons about being a person who is soft and circular rather than sharp and edgy. With an addictive “dumdididumdum” chorus fitting in between her evocative delivery of the verses, “Circle’s Dream” is an infinite joy to listen to and one of the best vocal performances K-pop’s seen this year. -- T.H.

8. EXID, “Night Rather Than Day” (Eclipse)

“Night Rather than Day” serves up slivers of jazz that have been retrofitted to sound like a dance track. A brass section accents the backdrop of breezy synths. This single is a departure from the outsized funk heard EXID’s sexualized tracks like “Hot Pink.” On-the-nose innuendoes are traded in for coquettish lyricism, urging a love interest to “come at night not during the day.” It’s a sonic deviation that cemented the girl group’s upward trajectory as their Eclipse EP hit No. 4 on the World Albums chart. -- C.K.

7. The Rose, “Sorry” (Sorry)

Few Korean acts are able to make a major impact straight out of the door, but The Rose’s impressive pop-rock song, “Sorry,” is undeniably one of the year’s strong points. Featuring intensely evocative vocals and a melancholic brand of instrumentation that rises and falls with the heart-wrenching ballad's emotional tension, the rookie quartet delivered an unapologetically glorious listening experience. -- T.H.

6. IU, “Palette” (Palette)

IU likes things a little old-fashioned in an industry that prizes ever-changing trends. But she proved that she’s more than relevant in 2017 when she returned to the music show circuit for the first time in four years with “Palette.” The track sounds like something Dev Hynes could’ve produced given the softly sung R&B, dreamy synth-pop production and neon decor of her comeback performance. One of the biggest stars in K-pop, G-Dragon, has a verse on this track. But the veteran idol isn’t stealing any scenes here: His whole verse is focused on uplifting IU as she sifts through her neuroses and reflections. The mellow-dy belies a topsy-turvy world of self-satire, idiosyncratic sound effects and throwbacks to older eras. Who knew self-examination could sound so catchy? -- C.K.

5. BTS, “Spring Day” (You Never Walk Alone)

While "DNA" and the "MIC Drop" remix were their (excellent) chart breakouts, BTS' historic Hot 100 run in 2017 was foreshadowed when "Spring Day" cracked the Bubbling Under Hot 100 ranking -- all the more important when considering the subject matter of the single. Detailing an internal winter inside them over missing someone, BTS touch on their past song material like mental health and depression, yet by the track's completion, there is a change when they realize the comfort and warmth that inevitably comes at the end of a tough period. That mindset showed an artistic turning point for the band, who have now evolved past a one-track mind with their music and lyrics, as the guys set the groundwork for their biggest material to date. -- J.B.

4. Red Velvet, “Red Flavor” (The Red Summer)

You'd be hard-pressed to find a pop song with a more uplifting, addictive, deliciously bubblegum melody than "Red Flavor." After sending listeners for a bit of a trip on the outrageous funk anthem "Rookie," the ladies of Red Velvet returned in July to deliver such a sweet track that fans will inevitably be hoping for something just as yummy next summer. -- J.B.

3. Sunmi, “Gashina" (Sunmi Special Edition Gashina)

The word “Gashina” has multiple meanings: leaving, thorns and a derogatory term for a woman. And Sunmi may or may not be seizing on all of them in this self-affirmation kiss-off to an undeserving lover. This moody torch song singles out a former love interest for leaving her. The dark synth-pop track incorporates dancehall elements, and its triple hi hats sound like marching drums. Her breathy vocalizations sensually emotes lyrics like, “Why are you leaving the pretty me here?” The edgy banger is also responsible for one of South Korea’s most imitated dance routines of the year as Sunmi turns finger guns into the physical manifestation of slayage. Her first solo outing since the disbandment of Wonder Girls, “Gashina” topped Korea’s Gaon Digital Chart and hit No. 3 on World Digital Songs. While she rises out of the ashes of a lost love, her solo career is reaching new heights. -- C.K.

2. Heize, “Don’t Know You” (/// (You, Clouds, Rain))

2017 was undoubtedly a huge year for soloists, and Heize was one of the brightest shining stars. A singer-rapper who initially broke out on female hip-hop survival show Unpretty Rapstar, Heize found her groove in a perfect pairing with production duo GroovyRoom, who crafted sleek R&B cuts that uplifted and enhanced the star's velvety vocals. Among her slew of hits this year -- from the pensive electro-ballad "In the Time Spent With You" to the jazz-tinged ballad "You, Clouds, Rain" -- her standout single has to be "Don't Know You." The moving R&B cut brilliantly blends a mix of lively beats and impassioned vocals, pierced by an undeniable sense of melancholy as the star admits to taking a lover for granted. The song pulls the listener in a ton of different directions, leaving them unable to be sure exactly how to feel by the end. "Don't Know You" requires an immediate replay for the listener to sort out their emotions. -- J.B.

1. Wanna One, “Energetic”

No one watching the K-pop scene can deny the power of Produce 101, the reality singing competition that whittles down 101 K-pop hopefuls to a temporary superband. Season 2 winners Wanna One perfected the sensational formula with their debut release, as "Energetic" utilized the EDM theme pervasive throughout the show, but in a slick, emotionally tinged style that allowed the guys to showcase their personalities and individuality. After watching the full season and voting these 11 individuals into their group, fans even got to choose "Energetic" as the single to release, picked over the more bombastic and aggressive "Burn It Up," making Wanna One's story all the more meaningful to their supporters.

Yes, "Energetic" is a pristinely produced, dynamic electro-pop gem that secures its performers as next-generation superstars. But all that went into its release -- from the season-long support from viewers to the song's genre and how fans got a personal say in the promoted song -- all represent the different pieces that make "Energetic" more than just a powerful pop single. It has a deeper story and meaning, all making special hallmarks of a year-defining K-pop track that undeniably celebrates a key moment in the music scene's history. -- J.B.