Grunge is a rock n' roll sub-genre that rose out of Seattle to gain worldwide prominence during the nineties.
A hybrid mix of heavy metal and punk rock, grunge is characterized as much by its sense of anti-fashion as it is by the music itself. Bands like Soundgarden became known as much for their flailing hair and flannel clothes as for their riff-heavy rock. This was best shown in a movie about the scene called Singles, which also boasted a grunge-heavy soundtrack featuring Seattle bands Screaming Trees and Alice In Chains.
The genre first gained notice in the late eighties as Seattle bands like Mother Lovebone, Mudhoney, and Tad drew crowds to dreary clubs like the OK Hotel and the Offramp, and released records on indie labels like C/Z and Sub-Pop.
When Nirvana's album Nevermind became a surprise megahit, the secret was forever out. Hit records by Pearl Jam, Alice In Chains, and Soundgarden quickly followed suit, spawning imitators like Bush and Stone Temple Pilots.
By the late-nineties, the tragic deaths of Andrew Wood, Kurt Cobain, and Layne Staley had taken their toll and grunge began a gradual fade.
The influence of grunge is still strong however, as are its fans who you'll find at blogs like LameStain and the Grunge Forum.