[troutman]

The Grandfathers of Grunge: Iggy Pop & Stooges, Neil Young & Crazy Horse, Husker Du, Pixies, Replacements

Other Grunge/Rock you may have missed: Screaming Trees, Mudhoney, Sugar, Urge Overkill, Alice in Chains

Rock styles:

http://allmusic.com/cg/amg.dll?p=amg&sql=73:20

American Underground:

http://allmusic.com/cg/amg.dll?p=amg&sql=77:12147

SST, was also a crucial influence, releasing records by the Minutemen, the Meat Puppets, Husker Du, Dinosaur Jr., and other key bands who pushed the outsider’s aggression of punk into new and provocative directions. The Midwest proved to be a potent breeding ground for the American underground, with Minneapolis’s boozy but heartfelt the Replacements and Chicago’s brutally loud Big Black and Naked Raygun winning sizable cult followings, while Sonic Youth and the Swans were the rulers of a dissonant East Coast enclave, Texas’s nomadic psych-noise merchants the Butthole Surfers were leaving a trail of terror across the country, and Boston’s Mission of Burma proved both powerfully influential and prescient during their short lifespan. In the mid-'80s, the initial commercial breakthrough of R.E.M. (who were tangential members of the scene despite their presence on the semi-major label I.R.S.) at once gave the American underground new visibility and put the first chinks into the armor of the close-knit community.

Grunge:

http://allmusic.com/cg/amg.dll?p=amg&sql=77:2679

Using the sludgy, murky sound of the Stooges and Black Sabbath as a foundation, Grunge was a hybrid of heavy metal and punk. Though the guitars were straight from early '70s metal, the aesthetic of grunge was far from metal. Both the lyrical approach and musical attack of grunge were adopted from punk, particularly the independent ideals of early '80s American hardcore. The first wave of grunge bands — Green River, Mudhoney, Soundgarden — were heavier than the second, which began with Nirvana. Nirvana was more melodic than their predecessors and they also had signature stop-start dynamics, which became a genre convention nearly as recognizable as fuzzy, distorted guitars. After Nirvana crossed over into the mainstream, grunge lost many of its independent and punk connections and became the most popular style of hard rock in the '90s.

Indie Rock:

http://allmusic.com/cg/amg.dll?p=amg&sql=77:2687

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.