'''Grindcore''' is an [[extreme metal|extreme]] genre of music that started in the early- to mid-1980s. It draws inspiration from some of the most abrasive music genres including [[death metal]], industrial music, noise and the more extreme varieties of hardcore punk. Grindcore is characterized by heavily distorted, down-tuned guitars, high speed tempo, blast beats, and vocals which consist of growls and high-pitched screams. Early groupslike [[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 variety of "microgenres" have subsequently emerged, often used to label bands according to alternative traits that deviate from standard grindcore, including [[goregrind]], focused on horror themes, and pornogrind, fixated on pornographic lyrical themes. Other offshoots include noisegrind (especially raw and chaotic) and electrogrind (incorporating electronic elements). Although an influential phenomenon on hardcore punk and other popular genres, grindcore itself remains an underground form of music.