Songfacts®:

• This steamy tune finds Calvin Harris joining forces with Sam Smith. The British white soul singer croons about wanting a hookup that probably won't lead to anything more. Smith is best known for his emotional singing in songs like "Stay With Me" and "Too Good At Goodbyes" and this represents his second foray into EDM following "Latch," his collaboration with Disclosure.
• Both artists co-penned the song with Canadian singer-songwriter Jessie Reyez, who also provides additional vocals. Reyez previously contributed to the writing of Calvin Harris' collaboration with Dua Lipa, "One Kiss."
• The Emil Nava-directed joyous video celebrates New York City's ball culture and its voguers as they show off their best moves. The clip features a glamorous cameo from the model Winnie Harlow, who walks a catwalk with some of the dancers.
  
  We see Smith delivering his lyrics in the downtown warehouse-turned-glittery dance club as well as other locales. Harris makes a few appearances too.
• This song was Calvin Harris' eighth UK #1 of the 2010s, making him officially the act with the most chart-toppers in the 2010 decade. The Scot was previously tying with Jess Glynne and Tinie Tempah on seven apiece.
• The song appeared as a bonus track on Smith's 2020 album Love Goes.
• Smith didn't know what to expect when they first met up with Calvin Harris.
  
  "I was like, is this, you know, what does he do? Because some people in the studio, it's like 'oh, you don't play an instrument'. Like you don't actually make the music. You're more of a taste maker, which is fab," Smith told BBC Sounds' Sidetracked with Nick Grimshaw and Annie Mac. "But he does everything himself. And I was immediately just enamoured by his talent. We just had so much fun making 'Promises.' It was the funnest day. I think you can hear that in the writing."