Grindcore is a type of heavy metal and hardcore punk music. It was invented in the 1980s by bands such as Napalm Death. Grindcore is a lot like black metal and death metal, but the guitar parts are very simple and are played over and over again in a song. The vocals are usually loud shouts and screams while the drums play fast and loud, around 200bpm. In most cases, grindcore songs will be very short in length - Napalm Death's song 'You Suffer' is the shortest in the world at 1.316 seconds long. Their lyrics are similar to death metal and hardcore punk, which usually sing about pain, suffering, blood, gore or politics, injustice and revolution.
One popular grindcore band is Anal Cunt, who go by "A.C." because their name has a sexual meaning. A.C. sings about racism, violence, and sexism. They produce very controversial songs such as 'You Were Pregnant So I Kicked You in the Stomach' and lyrics which make jokes of the Third Reich.
There are several offshoots of grindcore, including pornogrind, goregrind and deathgrind.