A sub-genre of UK Garage.
It is hard to tell when it really began, however 'grime' got more and more popular after releases such as Pulse X (Musical Mob) and Eskimo (Wiley Kat). Big players around that time included Wiley, Musical Mob, Black Ops/Jon e Cash and BigShot.
The idea was to make the composition dark, yet keep it simple, which MC's loved.
Many claim these 'basic' tunes can be made on a PlayStation, but then why is Grime still more popular than the classic UK G songs to this day?