Grindcore, often shortened to grind, is an evolution of hardcore punk, most commonly associated with death metal and crust punk. Grindcore is characterized by heavily distorted, down-tuned guitars, blastbeats, hardcore punk and crossover thrash influenced riffing, short songs, and a vocal style consisting of growls and higher-pitched vocals, often similar to those found in black metal. Lyrical concepts range from social and political issues to gore and horror to humor.