Originally used to describe the music of such bands as Stereolab, Disco Inferno, Seefeel, Bark Psychosis and Pram, it spread out to be frequently used for all sorts of jazz- and Krautrock- influenced, instrumental, electronica-added music made after 1994. Bands from the early 1990s such as Slint and Talk Talk were influential on this genre. As with all musical genres, the term is arguably inadequate: it is used for the music of Tortoise as well as that of Mogwai, two bands who have very little in common besides the fact that their music is largely instrumental.
After the second Tortoise LP Millions now living will never die, the band became a post-rock icon. After Millions... many bands began to record, inspired by the "Tortoise-sound" and were often described as post-rock. As diverse as post-rock is, so is Tortoise: one member of the band came from the Chicago jazz scene, another from the hardcore scene.
In the late nineties, Chicago became the home base of may different groups. John McEntire (of Tortoise) became an important producer for lots of them, as well as Jim O'Rourke (of Brice-Glace, Gastr del Sol and many more). Post-Rock began to range from very slow, guitar-ambient (for instance: the collective 'Boxhead Ensemble', led by Michael Krassner, featuring many famous artist: Will Oldham, Jim O'Rourke, Jim White, Mick Turner, David Grubbs, to name a few) to up-tempo, electronic music (Stereolab, whose music is not largely instrumental).
Canadian band Godspeed You Black Emperor, later renamed Godspeed You! Black Emperor brought a political element with Anti-globalization movement leanings. Several bands emerged as side-projects, including Shalabi Effect.
By the early 2000s, the term had started to fall out of favour, while the major artists kept on making high quality recordings. The wide range of styles covered by the term had robbed it of its usefulness almost from the moment it was coined.