Sometimes used interchangeably with "guitar pop rock", in the mid-1980s, the term "indie" (or "indie pop") began to be used to describe the music produced on punk and post-punk labels. Some prominent indie rock record labels were founded during the 1980s. During the 1990s, Grunge bands broke into the mainstream, and the term "alternative" lost its original counter-cultural meaning. The term "indie rock" became associated with the bands and genres that remained dedicated to their independent status. By the end of the 1990s indie rock developed subgenres and related styles including lo-fi, noise pop, emo, slowcore, post-rock and math rock. In the 2000s, changes in the music industry and in music technology enabled a new wave of indie rock bands to achieve mainstream success.
In the early 2000s, a new group of bands that played a stripped-down and back-to-basics version of guitar rock emerged into the mainstream. The commercial breakthrough from these scenes was led by four bands: The Strokes, The White Stripes, The Hives and The Vines. Emo also broke into mainstream culture in the early 2000s. By the end of the 2000s the proliferation of indie bands was being referred to as "indie landfill".
The term indie rock, which comes from "independent," describes the small and relatively low-budget labels on which it is released and the do-it-yourself attitude of the bands and artists involved. Although distribution deals are often struck with major corporate companies, these labels and the bands they host have attempted to retain their autonomy, leaving them free to explore sounds, emotions and subjects of limited appeal to large, mainstream audiences. The influences and styles of the artists have been extremely diverse, including punk, psychedelia, post-punk and country. The terms "alternative rock" and "indie rock" were used interchangeably in the 1980s, but after many alternative bands followed Nirvana into the mainstream in the early 1990s, "indie rock" began to be used to describe those bands, working in a variety of styles, that did not pursue or achieve commercial success. Aesthetically speaking, indie rock is characterized as having a careful balance of pop accessibility with noise, experimentation with pop music formulae, sensitive lyrics masked by ironic posturing, a concern with "authenticity," and the depiction of a simple guy or girl.
Allmusic identifies indie rock as including a number of "varying musical approaches compatible with mainstream tastes". Linked by an ethos more than a musical approach, the indie rock movement encompassed a wide range of styles, from hard-edged, grunge-influenced bands, through do-it-yourself experimental bands like Pavement, to punk-folk singers such as Ani DiFranco. In fact, there is an everlasting list of genres and subgenres of indie rock. Many countries have developed an extensive local indie scene, flourishing with bands with enough popularity to survive inside the respective country, but virtually unknown elsewhere. However, there are still indie bands that start off locally, but eventually attract an international audience.
Indie rock is noted for having a relatively high proportion of female artists compared with preceding rock genres, a tendency exemplified by the development of the feminist-informed Riot Grrrl music of acts like Bikini Kill, Bratmobile, 7 Year Bitch, Team Dresch and Huggy Bear. However, Cortney Harding pointed out that this sense of equality is not reflected in the number of women running indie labels.