A behind-the-scenes look at what went into making summer's hottest K-pop album.

From the frenetic synths of “Going Crazy” to the dreamlike melodies of “Walk on Memories,” EXO's latest album, The War, held nothing back from fans. Pulling inspiration from funk, reggae, EDM, trap and more, then weaving it all together through top-notch production, it proved a logical progression in their sonic journey and a summer-friendly successor to the group's darker previous album, Ex'Act.

With The War, EXO topped Billboard's World Albums chart for two consecutive weeks and went on to sell over 1 million copies globally, proving that the EXO-L fandom is sticking around for the boy band's evolution.

Learn what went into the hottest K-pop album of the summer from the members themselves and some of the producers behind its hottest tracks.

“The Eve”

Mike Woods: I was one of the producers on “The Eve” which was originally titled “Black Dress.” I wrote it alongside Kevin White, Andrew Bazzi and Henry Lau. Originally the song was for Henry Lau's project, but we all felt that it going to EXO would be best for everyone as it was a perfect record for them. The sound came about from us wanting something sexy and melodic, but also performance driven. We wanted to paint a dark and mysterious vibe, hence the title “Black Dress.” We wrote the song during a writing camp for SM [Entertainment] -- we basically write one to two songs a day for about 10 days and see what we come up with. “The Eve” came about on the fourth day of the camp and only took us one day to complete, from conception of music and lyrics to the final composition. We recorded the demo for the song the same day of conception.

“Ko Ko Bop”

Styalz Fuego: I went out to Seoul early November last year. It was maybe 10 of us ... and basically we were all put in the the SM studios for a couple of weeks. It was my first time out there. [You're] basically hearing a quick [overview] of the whole scene and everything that's going on in K-pop and then you're put in the rooms every day to just write songs. “Ko Ko Bop” was maybe the fourth of fifth day in. The first couple of days I was trying to get a hang of [it.] I listened to a lot of K-pop, but still, it's a different scene to write a song [for] because it's so much more complex. [K-pop songs] have so many more moving components to them, than say, if you're out in L.A. writing, trying to make things very simple and trying to get to the core of the lyric and have the beat as simple as possible.

I kinda knew as soon as we'd done the song and we played it back for everyone, just from the response we got to the song it was gonna be something, but I had no idea it'd be [EXO's]. Going into writing that song, it was basically to do something with the reggae feel, that was the main thing we were aiming for. It took a whole different direction with the crazy drop section after the chorus. We went into this doing a reggae-pop song and it transformed into what it is.

I don't think it was ever for EXO -- I think it was more for a female group. Shaylen [Carroll, co-producer] did the demo. When they did the playback for everyone at SM, [we thought] they would essentially understand this is for one of the girl groups. A girl is singing it and it's in the range of what the girls can sing. The song was actually in a higher key -- I think three semitones higher -- so it was more fitted for a female [group] originally.

But I guess it worked out well because we had a few of our voices in the song spread out, so I guess when they started picking where the song could go, it made sense for EXO because there are so many different sections vocally.

Shaylen Carroll: I wrote the lyrics and melodies with Tay Jasper, then I sang the demo. It's a “feel good” type of track, so the melodies came easily. Styalz's stuff is easy to write to. When I was recording some melody ideas I kept on singing nonsense phrases and one was “Shimmy shimmy Ko Ko Bop,” which we all thought was super quirky and catchy. So we built off that and turned it into something real. The song is about not worrying about things... Sometimes you just gotta go with the flow! Don't worry about the haters.

Jared Cotter, Shaylen's manager: [SM Entertainment] let us know it was being considered for a girl group.

Carroll: [I] definitely never thought it would get flipped to EXO, but obviously we are thrilled it did. We [knew] it was special when we finished it. I am really glad it found the home that it did.

Chen: [The members and I] wrote the lyrics separately and worked on putting the lyrics together for the song afterwards. We worked on the song using a special method, where we gathered all three of our lyrics for the song and selected which lyrics would suit the song the best. I don't think I have any regrets or wish that it could have better since it's the best result produced through all the effort that our members and other various writers have put into the process. Through the lyrics, I wanted “Ko Ko Bop” to have people shake off all their stress and enjoy themselves just as who they are.

Baekhyun: I felt that a lot of our fans were unable to fully enjoy our concerts or performances because they're conscious of what others would think. Since “Ko Ko Bop” is a reggae and EDM genre and it's easy to groove to, I wanted my lyrics to have people to become more carefree, release their stress and dance away with the music.

“What U Do?”

Ronny Svendsen: The song was written in Seoul last December. We went over to Korea to do a camp for SM with our, at the time, new publishing company called Ekko Music Rights. We tried to create a song that would be danceable and organic sounding with emphasis on real instruments -- bass, guitar, piano. The song was really based around the guitars and a simple chord progression. Sound-wise we had a reference from another boy band of SM Entertainment's called NCT, which we originally aimed for: danceable, but not “synthy.”

“Forever”

Greg Bonnick of LDN NOISE: This was written in Seoul with Kenzie and Adrian McKinnon. We knew the vibe was perfect for EXO so we worked on it for about a week on and off to get it right, trying different chords and toplines. The intro part was initially the chorus. We thought, “Great, we nailed it,” but once we listened back, it needed to go up another gear. We then added the extra section, which is now the chorus, and it came to life and made it so much bigger.

To be honest, we wanted to make a “Monster” 2.0 but still be different and bigger, you know? We always have fun when we can mix hard hip-hop verses with a bright chorus, and for a group like EXO, it gives it the perfect balance.

We wanted to make a statement: this song, this album, it's EXO forever. We feel really connected to this group and the fans so it's important we got it right, and the feedback has been amazing, so we are very happy.

“Diamond”

Harvey Mason Jr.: We went to Seoul to work with SM Entertainment artists and EXO was one of the artists that they asked us to write songs for. Generally, when we've written songs for EXO in the past, we listen to their material, we see where they are in their sonic journey, kinda figuring out where they fit as far as what type of music they're making right now and then we try and go one step further -- take them somewhere interesting. We just try and do things that are fresh and original but yet still sound like EXO. On this particular trip, we listened to their current material and then as a group, myself and JQ and some of the other guys, we sat down and said, “That's what they're doing? Let's beat it. Let's try and do something amazing.”

Patrick “j.Que” Smith: On this trip, they took us to an EXO show at the Olympic Stadium and to see them on the stage, see them performing the records and see the fans in the crowd... Getting to experience all of that was amazing. It kind of changed the perspective of what we were trying to create and how to create it, something that would live in that arena environment.

Mason Jr.: Yeah, seeing what people were reacting to and seeing them perform our last song [“Overdose”], seeing what made the crowd excited, [what] the guys were feeling when they were singing it... Seeing the concert and seeing 30,000 screaming people... I [went] back to the studio virtually that night, if not the next day, and having that energy and that vision of what they were doing, how they were performing... [We were] really trying to come with that energy.

Smith: So much of it came from watching the live show, because parts of the show [were] R&B-ish, then there were parts of the show that felt EDM-ish, and then there were parts where there were trap-like styles. The conversation became, “As opposed to trying to make one of these, let's create something different. Let's go in and make a movie. We're going to go in here and make an audible movie, we're going to give them three or four minutes of highs, lows.”

Mason Jr.: To us, there's really not something they can't pull off as far as pop music; they can do it all. They can sing, they can dance, they have the energy.... It's just all there for us. It's like a painter having every color to paint with.

“Touch It”

Denzil Remedios: From what I recall, “Touch It” came to Ryan [Jhun]'s hands first. He got the song originally from the Jackie Boyz [Carlos and Steven Battey] and the Fliptonez. I think they sent it to him while we were still in Korea and this was actually more than a year ago now, maybe close to almost two years ago when they sent that record, and it just kinda connected right away. We heard what it could be -- it already sounded like the guts of a smash was there, at least something we could put into a big group's hands. From there, Ryan and I did what we normally do, which is pick it apart and say, “Hey, what parts could get stronger? What could we do extra with the production to pump it a little bit more?” That's how we got the record, and then we just worked on all those elements over probably months back and forth.

“Touch It,” when we first heard it, already had such a non-today-ish vibe -- a classic vibe. It's not like the everyday pop EDM electronic-y sound that everyone's doing, which was refreshing when we first heard it. We were like, “Yo, this sounds like an old Justin Timberlake, almost Michael Jackson type of thing.” That old school vibe. We didn't wanna change the production or toplining to the point where it didn't sound like that anymore. When we were hearing it, sonically we were like, “Cool, this can be something that a group like EXO can take and use for the album and it doesn't sound like everything else they would normally be putting out.”

We were thinking stage performance at the time too. It's just a really fun track that doesn't have to be too serious -- you don't have to have crazy choreography where they drop from the top of the stadium.

Chen: My imagination provides the most inspiration for the lyrics. For “Touch It,” I played out the lyrics in my mind as if it is like a scene from a movie when writing it. After completing the draft, I worked on it by fixing awkward pronunciations by singing along the lyrics with the music. This helped me figure out more suitable and comfortable words that would enhance the groove when listening to the song.

“Chill”

Otha “Vakseen” Davis: We went to a song camp last year -- I wanna say it was November -- and it was probably the third camp my team has been on. Anytime we go to song camps at SM, they usually have a focus for us as far as what to work on and I know we worked on some things for EXO. For any creator, you always wanna try to make an EXO project. We fell in love with the vibe and the energy [of “Chill”] in the studio and SM's team felt the same way about the record. That happened to be one that everybody loved -- the guys loved it ultimately when they heard it.

There were certain elements like the breakdown in “Chill” that was added at the camp, but we came with the ideas already fleshed out. Ultimately, [the breakdown] was to serve as a dance breakdown. K-pop acts, especially EXO, are very performance-oriented, so you wanna have sections to show out. You wanna make something that feels good but still can allow them to move.

Chanyeol: Usually it's common to work on the lyrics based on a demo guide, but for the song “Chill” I worked on the lyrics with an empty track without demo lyrics. I think that’s part of the reason why the lyrics were able to come out pretty naturally.

“Walk on Memories”

Albi Albertsson: In early 2016, Wassily Gradovsky, who was actually interning for me as a producer at that time, brought an instrumental to me, which was later to become the instrumental for “Walk on Memories.” He had recorded a loop on the upright piano I have in my living room and incorporated it into this smooth R&B style beat.

I immediately liked the chord progression and the vibe of the track, so I sent it to Justin Reinstein, our writer from New York who we had just started working with at that time. He had a very smooth topline and vocal style that I thought would be perfect for this track, so he worked on the instrumental to craft the melodies.

From then on it was only finalizing the song: I added stacks of vocal harmonies and other details to make it work better for a group performance and make it more “K-pop,” added some vocal adlibs and then finalized the production by adding more instruments and finalizing the mix.

When I sent it to EXO's A&R, he immediately loved it but wanted a more distinct intro that reflected the fantasy theme he had in mind for the new album. So instead of the very basic intro the track originally had, I came up with a new, more mysterious and vibey intro, which is the intro you can hear in the final version of the song.

Wassily Gradovsky: The track was influenced by the genres of '90s R&B and jazz, reimagined with contemporary sounds. The arrangement of the piano chords -- being arpeggiated from bottom to the top -- was inspired by Justin Timberlake's “Cry Me A River,” but with a lighter and more positive tone. The slightly melancholic bridge, which is modulating into the final uplifting chorus, represents an uplifting, “happy ending” twist to the story.

“Going Crazy”

Otha “Vakseen” Davis: It was something that we did maybe around February of 2016. They loved it and for some reason could not find the right topline for it -- I think they had one originally and it didn't work at the end of the day. So they had this track, it was already placed on EXO and my team was presented with the opportunity to write to it. So I had one of my writers go in and do what he does. Funny enough, it was supposed to go on the Ex'Act album. It was something that they loved, but it didn't make sense then. We were persistent. Between myself and my business partner, we [would say], “Hey, what about this one? Don't forget this record!” Fast forward to now, the new album was coming out, [and] we were finally able to get them to connect. I think we had to make a couple of edits on it between that year or so passing just to make sure it was as fresh as possible.

The track's over a year old -- there's something so special about it because you drop it now, 2017, and it's still hot, still relevant. And that's the goal: create timeless music that can be good any time.