Songfacts®:

• This song has its origins in the Radiohead Kid A sessions. Thom Yorke told Rolling Stone magazine in 2006: "'Black Swan' has this tiny, shredded segment of something that was one of the library samples we had. It was Ed (O'Brien guitar) and Phil (Selway drums) doing this thing, and I sliced it into bits. The sample was 2000, but the song was 2005."
• In an interview with Mojo magazine February 2008, Thom Yorke confessed that one of the things from doing a solo album that he'd learned was that all the stuff he does on a laptop gets him excited because he can hear what he is going do vocally. However unless he has an actual vocal in place, it's a bit unfair to expect anybody else to understand what is going on. When asked to give an example Yorke replied: "I was playing bits of 'Black Swan,' 6 minutes of, er, mostly drivel, and Nigel's (Godrich the producer) like, 'Bloody hell! I'm not interested in any of this.' I said, I've been working on this for ages. It's great. 'No it's not,' he says. But as soon as I put the vocal on, he was like, 'OK, now it makes sense.' It reminded me just how important the voice is."
• This plays over the closing credits on the 2006 Richard Linklater movie A Scanner Darkly.