Grindcore started sometime in the early 1980s almost simultaneously in the U.K. and the U.S. The bands usually cited as grindcore pioneers are Siege and Repulsion from the U.S. and Napalm Death and Extreme Noise Terror from the U.K. Napalm Death's album "Scum" is thought to be the first grindcore release, according to the Grindcore website.
According to Noise Squatch Records,the name for this strand of heavy metal came from Napalm Death's description of their music---grinding hardcore. The band's bassist, Shane Embury, says the term best described the music they were into at the time---different kinds meshed together.
Grindcore has spawned a few subgenres, most notably goregrind and cybergrind. The former differs from grindcore lyrically more than musically, covering violent topics such as gore, rape or death. Cybergrind differs musically from the other two in that it uses synthesizers and computer-generated sounds.