The Hardcore genre surprisingly has one of the broadest terms of all EDM. There are dozens and dozens of sub-genres but they are incredibly varied. The term hardcore usually means music that is darker and harder, but not necessarily faster.
Hardcore as a word (in relation to EDM) can trace its roots to Belgium. A number of artists such as à;GRUMH… and later Leather Strip began to call their music hardcore techno. The origins of the name are largely rooted in this scene, although hardcore also regularly incorporated elements of house into its sound.
In the early 1990s, the hardcore sound began to introduce sped up hip-hop breakbeats, piano breaks, dub and low frequency basslines and cartoon-like noises, which has been retrospectively called ‘old skool’ hardcore, and is widely regarded as the progenitor of happy hardcore (which later lost the breakbeats) and jungle (which alternatively lost the techno style keyboard stabs and piano breaks). This is more or less down to the further development of the synthesizer and the very creative use of the Amen Break.