Songfacts®:

• Justin Bieber lends his voice to this song, which he also co-penned. The Canadian pop star's manager, Scooter Braun, shared on his Instagram: "Justin wrote this song in the studio one night just vibin out... I ran into Wes aka Diplo at a club and told him I had this great song and vocal by JB and we were figuring out what to use it for. He said can we hear it for Jack U. The rest is history."
• Diplo told Billboard magazine that it was a big deal when Bieber gave Jack U the song. "It's one of the strongest records he had on his album, but he had no production for it," he explained. "We transformed it into something different."
• Jack U is a collaborative project of DJ/producers Diplo and Skrillex. Asked during a 2015 Reddit AMA how Jack U came to be, Diplo replied: "Years ago I met Skrillex and gave him this song called 'Amplifier' - we didn't finish it but we made Jack U over the last year for fun in LA - late nights."
  
  Diplo added that he has lost the session that included "Amplifier" so sadly we will never get to hear the original Jack U track.
• The Brewer-directed video was shot at a Los Angeles art gallery in late May 2015. Neither of the producers appear in the clip, instead we see Bieber delivering his verses to the camera at different angles. There is a backdrop of photos of the pop singer and fans were invited into the gallery to graffiti the pictures, the results of which were edited into the visual. "Justin wrote this record during a tough time in his life and it comes to us that sometimes, as artists, we are also just objects and we have to take that as much as we have to use that to create," Skrillex and Diplo said. "We all do this for you, respect that you put us here and it's Ü that made the video."
• The Jack U name is a reference to the term "jack," which comes from Chicago house slang and recalls the act of frenetically dancing to a house beat. Skrillex explained to Billboard magazine: "Basically, Diplo and I were in a phase where we were obsessed with footwork - a spinoff of Chicago house where the whole jacking scene comes from. Jacking became this word that we used more and more, to the point where we started using it to describe things, like, 'Oh, that's jacking.' It's just really high-energy music - it jacks you up, you know?"
• During an interview with Radio.com, the comment was made to Justin Bieber that the song could probably be arranged for a band. The singer agreed, saying: "That's how I want it to be for all my songs. I want to be able to strip it down completely and say, 'What is the raw structure of this song? If we take everything else away, is it still a good song?' I think that's why it worked so well."
• The high-pitched squealing dolphin sound during the drop is actually Justin Bieber's pitch-shifted voice, as he's singing "I need you the most."
  
  "It was finding that one little thing which was the dolphin singing, the dolphin sound," Skrillex told The New York Times. "It's pitched way up, distorted, bounced, rebounded again, so it sounds worse almost."
• This song earned Justin Bieber his first Grammy Award when it won for Best Dance Recording. Bieber performed the song with Skrillex and Diplo at the ceremony. When Bieber got to the line, "gave you the shirt off my back," he demonstrated by actually taking his shirt off.