Songfacts®:

• "The Birthday Party" is four verses of stream-of-consciousness where Matty Healy reflects on the social minutiae of a house party. It starts off with the singer stepping back into the social scene after becoming clean.
  
  Hello, there's a place I've been going
  There's a place I've been going
  Now I'm clean, it would seem
  Let's go somewhere I'll be seen
  
  In 2018, Healy took a seven-week sabbatical at a rehab clinic in Barbados to battle a four-year addiction to heroin and benzodiazepines. Since then he has steered clear of drugs.
• Healy makes a reference to the American rock band Pinegrove and the accusation that their lead singer was involved in sexual coercion.
  
  They were gonna go to the Pinegrove show
  They didn't know about all the weird stuff
  
  By the third verse, things aren't going well, as Healy highlights his struggle to connect with others.
  
  In a boring conversation with a girl called Mel
  About her friend in Cincinnati called Matty as well
  You pulled away when I went in for the kiss
• Speaking with Dazed, Healy said he originally intended to do a song about "what it was like to be at a house party at 20, 25, and 29." Then he realized he just needed to write about what it's like now.
• John Waugh performs the sax solo. The musician tours internationally with The 1975, and also is a member of The New Standard and Extra Curricular.
• The animated video is set in a fictitious digital detox center called Mindshower, where Healy encounters assorted human-like characters – all taken from reddit / 4chan meme subculture. The band teamed up for the clip with director Ben Ditto and co-director/artist Jon Emmony, who worked together on their 2019 visual for "People."
  
  Ben Ditto said in a press release: "Matty and I have a shared fascination with the underbelly of Internet culture and how that impacts modern life, and we looked to address this from several directions and created an engaging and beautiful piece of filmmaking to contain these messages and their performance in a revolutionary way."
• Speaking on the Song Exploder podcast, Healy explained that he wrote "The Birthday Party" at the end of a relationship after relapsing for the first time since coming out of rehab. "Everything felt like it was drawing to end in a natural way. You put it into a song and it becomes romantic and exciting, but all those things are boring and sad in reality," he said. "I try and make art out of the boring, sad parts of my life, because it's better than them being boring and sad."
• The track is a rare example of The 1975 writing the arrangement together rather than Healy or his regular songwriting partner George Daniel coming up with the idea in its entirety.
• The "female" vocoder-sung lines were originally meant to be sung by a female chorus, but the band stuck with the demo sang by Healy. "First it was funny, then it was the best thing," the 1975 frontman said.