Grindcore is an extreme genre of music that originated in the early to mid-1980s. It draws inspiration from some of the most abrasive-sounding genres – including hardcore punk, thrash metal, crust punk, industrial and noise rock. Grindcore is characterized by a noise-filled sound that uses heavily distorted, down-tuned guitars, grinding overdriven bass, high speed tempo, blast beats, and vocals which consist of growls and high-pitched shrieks. Early groups like Napalm Death are credited with laying the groundwork for the style. It is most prevalent today in North America and Europe, with popular contributors such as Brutal Truth and Nasum. Lyrical themes range from a primary focus on social and political concerns, to gory subject matter and black humor.
A trait of grindcore is the "microsong". Several bands have produced songs that are only seconds in length. British band Napalm Death holds the Guinness World Record for shortest song ever recorded with the one-second "You Suffer" (1987). Many bands, such as Agoraphobic Nosebleed, record simple phrases that may be rhythmically sprawled out across an instrumental lasting only a couple of bars in length.
A variety of "microgenres" have subsequently emerged, often labeling bands according to traits that deviate from regular grindcore, including goregrind, focused on themes of gore, and pornogrind, fixated on pornographic lyrical themes. Other offshoots include noisegrind (especially raw and chaotic) and cybergrind (incorporating electronic elements such as sampling and programmed drums). Although an influential phenomenon on hardcore punk and other popular genres, grindcore itself remains an underground form of music.