Crust punk (sometimes simply crust) is one of the evolutions of anarcho-punk and hardcore punk, mixed with distorted extreme metal guitar riffs. The style, which evolved in the mid-1980s in the UK, often had songs with dark, pessimistic lyrics, lingering on the bleak aftermath of nuclear war. Crust is typically played at a fast tempo with growled and screamed vocals and anarchist lyrics. The guitar playing is similar to that used in speed metal and thrash metal. The bass guitar features more prominently and there is more use of distortion, producing a "bassy" and "dirty" sound.