The most rigid and extreme variation of punk rock, Hardcore Punk, was primarily an American sensation that took shape in Los Angeles and New York, with small, individual scenes dominating the east and west coasts soon after. Washington DC, Boston, and San Francisco played massive roles in the growth of the genre. Emerging in the early '80s, with the ideals of traditional punk firmly in tow, the blueprint for Hardcore was simple: play it louder, play it harder, and play it faster. The music was relentless, the songs were brief, the riffs were basic, the vocals were shouted or screamed, and the records looked (and sounded) like they were made in someone's basement. Many actually were, and the do-it-yourself (D.I.Y.) aesthetic that was later embraced by grunge and indie rock traces back to the early days of hardcore. Black Flag's Greg Ginn, Dead Kennedys' Jello Biafra, and Minor Threat's Ian MacKaye and Jeff Nelson started influential labels Alternative Tentacles, SST, and Dischord on shoestring budgets in order to put out their respective band's 7" records and home-recorded cassettes. Hardcore shows were often promoted with photocopied flyers, fanzines, and by word of mouth, as the underground fan base became increasingly devoted. For many, the term "hardcore" became a way of life, synonymous with shaved heads, slam dancing (later, moshing), sociopolitical ideals, and a stern attitude. Hardcore kept going into the '90s without ever breaking into the mainstream, though bands influenced by the hardcore aesthetic (including Nirvana and Green Day) became major rock stars, and former hardcore punkers like Bob Mould, Henry Rollins, Mike Watt, Ian McKaye, and Dinosaur Jr.'s J Mascis became alternative icons. After spawning various similar-minded genres -- skate punk, speed metal, thrash, grunge, sludge metal, and metalcore, among others -- hardcore continued to flourish on a smaller scale through the 2000s.