Songfacts®:

• "By Your Side" is a bright and bouncy tune that harks back to Calvin Harris' early and mid-2010s singles. Released on June 4, 2021, when many artists were dropping music influenced by the COVID pandemic, it's a throwback to happier times.
  
  Harris told Apple Music's Zane Lowe he'd started on the song a while back but had forgotten about it until he was going through some of his old demos. When he listened back, it jumped out at him and Harris thought, I should finish this. "It felt nostalgic to me in a nice way," he said. "The sort of thing that nobody else is making."
• Singer-songwriter Tom Grennan is the guest vocalist. He gives a comforting message to a love interest, assuring her he will always be by her side when she needs him.
• Harris told Apple Music that Grennan was his first pick to be the singer. He'd liked his voice ever since he first heard his music, and once he started to follow Grennan on Instagram, Harris was struck by the "relentless positivity in his posts." After the Scottish producer completed the song, Grennan seemed an obvious choice.
• This is not Tom Grennan's first time on a dance number. He previously sang on Chase & Status' 2016 single "All Goes Wrong ."
• Harris and Grennan wrote the song with:
  
  Tom Grennan's "Little Bit Of Love" co-writers Jamie Scott and Mike Needle.
  
  English white soul singer-songwriter John Newman, who previously supplied guest vocals for Harris' 2014 UK #1 single "Blame."
  
  Hurts lead singer Theo Hutchcraft. He sang on another of Harris' UK #1 singles, 2013's "Under Control," and also appeared in the video for his 2012 song "Thinking About You."
• Tom Grennan was on the toilet scrolling through his Instagram messages when he saw Calvin Harris had contacted him. Harris told him, "I've got this song that I've had for like three or four years and I've just found it in my library of songs and I feel like you could really fit nicely on this song and are right for this song."
  
  Grennan sent Harris his vocals back two days later then the Scottish producer told him it was going to be his next single. "Literally the turnover from what wasn't a song to what is now 'By Your Side' was so quick because usually these things take months, but it wasn't," he recounted to Jessie Ware on her Table Manners podcast. "It was like three or four weeks, which is crazy."
• Tom Grennan included "By Your Side" as a bonus track on his Evering Road (Special Edition) album.