In an interview with the New Musical Express December 8, 2007, vocalist Thom Yorke was asked if songs like "All I Need" are about obsession. He replied: "That's why it's called 'In Rainbows.' That obsession thing, thinking beyond where you are at the time. It's a phrase I had for a while, it kept coming up in my notebooks. And I don't know why, because it's kind of naff. But it seemed to work-it's one of those weird things. It stuck and I don't know why."

The lyric "I'm (just) an insect" is a direct quote from New Wave UK band Magazine's 1980 track "A Song From Under The Floorboards." Magazine front man Howard Devoto's existentialist lyrics were an early influence on Thom Yorke.

In the same New Musical Express interview, Thom Yorke spoke about the complexity of recording the songs on the album. He said: "We deliberately did this thing to get a series of disembodiment when we were assembling tracks. So the vocal may be from one version or the drums may be from another. If there was something that you were particularly fond of you kept it from that take and forced it on the other version. For instance 'All I Need' was the outcome of four different versions of it. It was all the best bits together."