Songfacts®:

• There was a time when the term "NDA," meaning a non-disclosure agreement, was known only to those familiar with corporate jargon. But in the 2010s, more and more companies started requiring their workers and contractors to sign these agreements, and it became a political issue. By the 2020s, most folk knew what an NDA was, and Billie Eilish even used it as the title of this song, which finds her detailing fleeting love and her struggles to adjust to fame.
  
  On the track, Eilish recalls an encounter with a stalker, and buying a secret house to hide away. When she invites a "pretty boy" over, she gets him to sign a NDA on his way out.
  
  As usual the song was co-written and produced with her brother Finneas.
• During the second verse, Eilish fantasizes about giving up her music career and escaping to a tropical paradise such as Kaua'I, Hawaii.
• The final verse is intentionally ambiguous about a romance. Whether Eilish is singing of the "pretty boy" or another love interest is unclear.
  
  Think I took it too far when I sold you my heart
  How'd it get so dark?
  I saw stars
  
  She told Apple Music: "What I love about that part is that even I who wrote it and Finneas who wrote it, that little ending, I have eight different meanings for that. Each time I hear it, I think of a different thing. I love that, it makes me feel very fulfilled."
• This is the fifth single Eilish released from her second studio album, Happier Than Ever. Besides musing on fame, the record finds the teenage starlet expressing her frustration about emotional abuse, sexual misconduct and mistrust.
  
  "Almost none of the songs on this album are joyful," she told Rolling Stone. "I went through some crazy s--t, and it really affected me and made me not want to go near anyone ever. I don't know how to explain this, but all the songs on the album feel like a specific time, because they feel like when I wrote them and made them. It's so funny that to the rest of the world it's going to feel like a certain moment for them, and it's going to be so different than mine. That's such a weird, weird thing to wrap my head around."
• Billie Eilish directed the video herself. It shows the pop star singing in the middle of a dark two-lane highway as 25 stunt drivers in cars weave around her. The clip was all shot in one take with no stunt doubles, green screen or visual effects used for the speeding cars.
• Billie Eilish understands fully that some topics she sings about on Happier Than Ever may not apply to her fans, such as signing an "NDA." To ensure their more relatable, she centers on the feelings involved rather than focusing on the specifics. "I know that I try to, even when writing about stuff like that that's very isolating and not very relatable or consumable," the enigmatic pop star told Audacy's Julia. "I try to make sure it remains important to have things be interpretable."
• Billie Eilish gave the song its live debut on September 20, 2021 during her headlining set at Las Vegas' Life Is Beautiful festival, her first full set since the COVID lockdown. She also gave the live premiere to another Happier Than Ever track, "I Didn't Change My Number."