I think
allmusic has the best definition ... I especially agree with the whole macho aspect of post-nirvana "alternative" music that is distinctly lacking in indie music, which is pretty damn fey
But I would also agree with others on here that major label bands are now imitating the sound of indie label bands, and it blurs the line a lot ...
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Indie rock takes its name from "independent," which describes both the do-it-yourself attitudes of its bands and the small, lower-budget nature of the labels that release the music. The biggest indie labels might strike distribution deals with major corporate labels, but their decision-making processes remain autonomous. As such, indie rock is free to explore sounds, emotions, and lyrical subjects that don't appeal to large, mainstream audiences -- profit isn't as much of a concern as personal taste (though the labels do, after all, want to stay in business). It's very much rooted in the sound and sensibility of American underground and alternative rock of the '80s, albeit with a few differences that account for the changes in underground rock since then. In the sense that the term is most widely used, indie rock truly separated itself from alternative rock around the time that Nirvana hit the mainstream. Mainstream tastes gradually reshaped alternative into a new form of serious-minded hard rock, in the process making it more predictable and testosterone-driven. Indie rock was a reaction against that phenomenon; not all strains of alternative rock crossed over in Nirvana's wake, and not all of them wanted to, either. Yet while indie rock definitely shares the punk community's concerns about commercialism, it isn't as particular about whether bands remain independent or "sell out"; the general assumption is that it's virtually impossible to make indie rock's varying musical approaches compatible with mainstream tastes in the first place. There are almost as many reasons for that incompatibility as there are indie-rock bands, but following are some of the most common: the music may be too whimsical and innocent; too weird; too sensitive and melancholy; too soft and delicate; too dreamy and hypnotic; too personal and intimately revealing in its lyrics; too low-fidelity and low-budget in its production; too angular in its melodies and riffs; too raw, skronky and abrasive; wrapped in too many sheets of Sonic Youth/Dinosaur Jr./Pixies/Jesus & Mary Chain-style guitar noise; too oblique and fractured in its song structures; too influenced by experimental or otherwise unpopular musical styles. Regardless of the specifics, it's rock made by and for outsiders -- much like alternative once was, except that thanks to its crossover, indie rock has a far greater wariness of excess testosterone. It's certainly not that indie rock is never visceral or powerful; it's just rarely -- if ever -- macho about it. As the '90s wore on, indie rock developed quite a few substyles and close cousins (indie pop, dream pop, noise-pop, lo-fi, math rock, post-rock, space rock, sadcore, and emo among them), all of which seemed poised to remain strictly underground phenomena.
