After the failed experiment of 1967's Their Satanic Majesties Request, the Rolling Stones knew it was time to return to a more basic rock sound. The "Jack" in this song is actually Keith's old gardener, Jack Dyer; Jagger crashed at Keith's place one night and the sound of Dyer walking around in his rubber boots woke Mick up. He asked Keith about the noise. "Oh, that's Jack. That's Jumping Jack." From that tiny spark, they sat down together and wrote one of their biggest hits.
In many ways, the track launched a whole new phase of the band's career. A crappy follow-up to Their Satanic Majesties Request could have easily sent the band into a downward spiral, but they bounced back in a bigger way than almost anyone could have imagined possible.