Indie rock is a sub-genre of alternative rock that originated in the United Kingdom and the United States in the 1980s. The meaning of the term "indie rock" is contested today by many musicians, fans and commentators. Most use the term "indie" to describe any rock music produced by artists working within the network of independent record labels and underground music venues that emerged in the United States and elsewhere in 1980s and 1990s. Others see indie rock as a distinct genre of rock music with a specific artistic aesthetic, and care less about the context in which it is made. Many embrace both meanings of the word, believing that the aesthetics of the genre and its means of production are deeply intertwined.

Indie rock artists are known for placing a premium on maintaining complete control of their music and careers, releasing albums on independent record labels and relying on touring, word-of-mouth, airplay on independent or college radio stations and, in recent years, the Internet for promotion. However, in the 2000s many acts with a musical style identified as "indie" signed to major record labels or their subsidiaries, and began promoting themselves through more traditional media outlets. This has led to a further blurring in the meaning of the term.

The 1990s brought major changes to the alternative rock scene. Grunge bands such as Nirvana, Alice in Chains, Soundgarden and Pearl Jam broke into the mainstream, achieving commercial chart success and widespread exposure. Punk revival bands like Green Day and The Offspring also became popular and were grouped under the "alternative" umbrella. The meaning of the term "alternative" changed as mainstream success attracted major-label investment and commercially-oriented or manufactured acts with a formulaic, conservative approach. With this, "alternative" lost its original counter-cultural meaning and began to refer to the new form of music that was now achieving mainstream success. The term "indie rock" became associated with the bands and genres that remained underground.

The 1990s saw the emergence of several defining movements within indie rock. The lo-fi movement was spearheaded by Beck, Elliott Smith, Pavement, Guided by Voices, Neutral Milk Hotel and several bands associated with the Elephant 6 Recording Company such as Of Montreal and The Apples in Stereo. It placed a premium on simplistic recording techniques (including home recording), ironic detachment, and disinterest in "selling out" to the mainstream alternative rock scene.

The emo movement, which had grown out of the hardcore punk scene in the 1980s with bands like Rites of Spring, gained popularity as the 1990s progressed. Sunny Day Real Estate, The Promise Ring, The Get Up Kids and others brought a more melodic sound to the genre. Weezer's Pinkerton introduced the genre to a wider and more mainstream audience. Years later, the term "emo" would be applied to a wider variety of more mainstream bands by the music press.

Talk Talk's Spirit of Eden and Laughing Stock and Slint's Spiderland, provided the catalyst for the development of post-rock and math rock. Post-rock, an experimental style influenced by jazz andelectronic music, became recognized as a genre as Tortoise and their Chicago peers gained a national following in the middle part of the decade. Math rock shares similar experimental aesthetics, but is generally denser and more abrasive. Don Caballero, Chavez and others contributed to its rise in popularity during the 1990s.

In the 2000s, the changing music industry and increased use of the internet as a tool for music promotion allowed a number of indie rock bands to achieve mainstream commercial success. Modest Mouse was one of the first popular indie acts of the 1990s to make the jump to a major label, signing with Epic Records in 2000. Their 2004 album Good News for People Who Love Bad News was nominated for a Grammy Award for Best Alternative Rock Album. After many years with the Barsuk label, Death Cab for Cutie signed to Atlantic Records in 2004. Their 2005 album Plans was nominated for the Grammy Award for Best Alternative Album of that year and charted on the Billboard charts for 47 consecutive weeks and attained Platinum sales. In November 2004, two Bright Eyes singles, "Lua" and "Take It Easy (Love Nothing)", reached the two top spots on the Billboard Hot 100 Single Sales. In 2010, Arcade Fire's album The Suburbs reached number 1 on the Billboard charts in the United States and the United Kingdom. The following February the group won one Grammy Award (out of three nominations) for Album of The Year. The Walkmen, LCD Soundsystem, Vampire Weekend, Interpol, Spoon, MGMT, Grizzly Bear, The Killers, The Wombats, and The National have also enjoyed mainstream popularity. Reasons suggested for this success include the decline of record sales and increased media exposure of indie artists due to internet marketing.