Songfacts®:

• The lead single from Lady Gaga's fifth album, the singer co-wrote and co-produced the dance-pop tune with Tame Impala singer Kevin Parker, Anglo-American producer Mark Ronson and BloodPop, who co-produced Justin Bieber's single "Sorry."
  
  Gaga explained on BBC Radio 1 Breakfast Show that Parker flew to join her at Shangri La Studios, Malibu from Australia with the idea of a song called "Illusion." Gaga penned the lyrics on her Underwood typewriter, with the songwriters knocking it into shape in the studio.
• Ronson said of working with Gaga: "I knew her from just before she got really massive. She came and worked on a Wale song I worked on called 'Chillin'.' We both grew up on the Upper West Side of New York. She's a muso at heart. She loves sitting at a piano and barking orders at a drummer. She's one of the great voices in pop."
• Speaking on the Breakfast Show, Gaga explained the lyrics are a commentary about social media, how people try to create an idealized version of their lives and the need to accept most things we see on the Internet "aren't reality."
  
  "I believe many of us are wondering why there are so many fake things around us," she said. "How do we navigate through social media? How do we look through these images that we know are filtered and altered, and decipher what is reality and what is a perfect illusion?
  
  There are also a lot of things on the internet that are not reality. And I think people are pressured to keep that personal illusion going on in their real lives.
  
  So this song is about raging against it and letting it go. It's about wanting people to re-establish that human connection."
• Gaga described the song during an interview on iHeartRadio as "about modern ecstasy... We found our sweet, simple, ragey way of saying it. I get this sick adrenaline rush every time I hear it."
• Queens Of The Stone Age vocalist Josh Homme is among the musicians featured on the track. He is credited with guitar along with Kevin Parker and Mark Ronson.
• Fans have speculated that the lyrics could be inspired by Lady Gaga's former fiancée Taylor Kinney, with whom she broke up earlier in 2016. However, the singer denied this was the case. "I love Taylor so, so much and this song is not a hit out against Taylor," she told SiriusXM's Andy Cohen. "This song is just about... I'm sure not only feelings that I've had but that he's had, that my friends have had, my sister has in her relationship... it's a record about all of us. And I would never use my song or want to use the public to hurt anyone that I love so much."
• The video was filmed in the desert outside Los Angeles over two days. It was directed by fashion photographer and filmmaker Ruth Hogben, who previously collaborated with Gaga on video footage for the Monster Ball and ArtRave: The Artpop Ball tours. Mark Ronson, Kevin Parker, and BloodPop, all have cameos in the clip.
• The song topped the singles charts in France and Spain, but failed to make the Top 10 in many other countries, including the UK and US.