Indie rock is an umbrella term to reference artists that are or were unsigned, or have signed to independent record labels, rather than major record labels. Originally the term was not a reference to a genre of music; however, it has come to be used often to reference the sound of specific bands and the bands they have influenced. "Indie rock" is used as an umbrella term covering a wide range of artists and styles, connected by some degree of allegiance to the values of underground culture, counterculture, and (usually) describable as rock music. Genres or subgenres often associated with indie rock include lo-fi, post-rock, sadcore, C86, and math rock, to list but a few; other related (and sometimes overlapping) categories include shoegazing and indie pop.

Indie rock artists place a premium on maintaining complete control of their music and careers, releasing albums on independent record labels (sometimes their own) and relying on touring, word-of-mouth, and airplay on independent or college radio stations for promotion. Some end up moving to major labels, often on favorable terms won by their prior independent success.