"Rez" is a non-album track by Underworld, originally released in 1993 in the UK. It became one of their biggest club/live anthems despite the fact it could not be found on an album. However, it did appear on many compilations, b-sides, and even appeared on a bonus disc for Second Toughest in the Infants (1996). The first promo release of the single was pressed onto pink vinyl, and is highly collectible as it has another non-album track, Why, Why, Why. Due to this track's obscurity, there are, incidentally, many bootlegs of it. The more common release has "Cowgirl" on it. There is also a limited white vinyl pressing available in the US.
The text "CLOUD HAT REMEMBER THIS" is etched into the run-out groove of the COLLECT 002 12".
Unofficial bootleg remixes of 'Rez' / 'Cowgirl' by breakz DJ's 'Atomic Hooligan' were deemed good enough by Underworld's record label and lead to their inclusion as remixers of "Born Slippy .NUXX 2003" in 2003
The White Island EP (CD & 2x12") by Salt Tank features a track inspired by Underworld's "Rez". "Rezmorize", as the name suggests, is an homage to Underworld's famous instrumental track.
Underworld's labelmates, Futureshock, were also inspired by "Rez"'s b-side, "Why, Why, Why", which is sampled heavily in "The Question", and was released on the JBO label offshoot, Fuju.
After hearing the song at a performance, Tetsuya Mizuguchi decided to rename his at-the-time work in progress game from K-Project to Rez. The name stayed into its release.