Deep Dubstep is a descriptor for the darker, more bass heavy type of Dubstep in which the genre has its roots. Though it is fairly prominent in many countries worldwide, the beginnings of Dubstep lie in the UK. Dubstep cannot really be appreciated without a subwoofer, as it is defined by its low end bass, in comparison to its mid-heavy mainstream cousin.
Dubstep is typically produced at 140bpm. Tracks are relatively sparse, giving the bass and the percussion room to breathe, and as a positive side effect it also allows for interesting layering and mixes during DJ sets. Though earlier Dubstep productions had lighter Dub, Reggae and Garage influences, modern Dubstep has a darker and more sinister sound to it.
This is the genre that also popularised the LFO wobble bass, which became a heavily used method of providing variations in the bassline.