Tortoise's almost entirely instrumental music defies easy categorization, and the group gained significant attention from their early career. The members have roots in Chicago's fertile music scene, playing in various indie rock and punk groups. Tortoise was among the first American indie rock bands to incorporate styles closer to Krautrock, dub, minimalism, electronica, and various jazz styles, rather than the standard rock and roll and punk that had dominated indie rock for years.
Some have cited Tortoise as being one of the prime forces behind the development and popularity of the post-rock movement. Others, however, have characterised Tortoise's music as being heavily indebted to progressive rock.
Other groups related to Tortoise include The Sea and Cake, Brokeback, Slint, Isotope 217, and the Chicago Underground Duo. Tortoise records on the Thrill Jockey label.
The group's origins lie in the late 1980s pairing of Doug McCombs and John Herndon, who imagined themselves as a freelance rhythm section (like reggae legends Sly and Robbie). That idea never saw fruition, but their interest in grooving rhythms and recording studio trickery led to partnerships with drummer John McEntire and bassist Bundy K. Brown (both formerly of Bastro) joining, followed by Dan Bitney. Though songs are credited to all the musicians, McEntire quickly became perceived as, if not the acknowledged leader, the group's guiding force. In reality his extra contributions mainly took the form of being the recording engineer and mixer.