Grunge was both a musical style and a fashion choice. The music was generally defined by heavy guitars and overwrought, angsty lyrics; the fashion by flannel shirts, combat boots, muted colors and an overall blue collar aesthetic. If those elements seem a bit vague, that's because grunge was as much a rejection of other fads as a specific fad itself.
In the 1980s, popular rock music was dominated by flamboyant bands with teased hairstyles, neon spandex stage costumes, slick music production and a party-all-the-time attitude, like L.A.-based bands Mötley Crüe and Poison [source: Billboard]. An eventual backlash was inevitable, and it came initially from the Seattle music scene. There, a small indie record label called Sub Pop signed edgy bands like Mudhoney and Nirvana.
Nirvana's unexpected jump to mainstream success defined grunge and the "Seattle sound" as a whole. Indeed, many of the bands who are lumped together under the grunge label (Pearl Jam, Alice in Chains, Soundgarden) have little in common other than their home city, a love of heavily distorted guitars and dark lyrics about serious topics. They all painted a stark contrast to the glam rock and hair metal that had come before, however. Of course, that meant that it wasn't long before you could buy fashionably grungy flannel in every mall in America.