Dubstep is a genre of electronic dance music that originated in South London, England, that generally features syncopated drum and percussion patterns with bass lines that contain prominent sub bass frequencies. The tempo is usually around 140 BPM and the snare will hit down on the third beat, this makes dubstep easily mixed with 70 or 140 BPM tunes.
Dubstep emerged in the early 2000's as a development within a lineage of related styles such as 2-step garage, broken beat, drum and bass, jungle, dub and reggae. It evolved in parallel to grime, which has often been interlinked with it, but is distinct and has its own tag.
It is a common misconception that the term dubstep was coined in 2002 by Ammunition Promotions in a press release sent to XLR8R magazine. In reality, the term was first uttered by DJ Hatcha. The origins of the genre can be traced back to the growth of the Jamaican sound system party scene in London and it's cultural influence since the early 1980s.
Post-dubstep, many of the key artists took their production techniques into earlier styles such as house, techno and UK Garage. Some of this material is hard to accurately describe and is sometimes referred to by the umbrella term Bass Music, which has its own tag, but this should be used sparingly, where no more precise tag exists.