Can someone tell me wtp "dubstep" actually is?

Getting off for now to do some more Japanese and then go to sleep. Before I go I'll post some tracks which I don't even know what the hell genre they fall in. They're slightly computerized, but real instruments still have a heavy role in them. Slightly ambient and glitch? Songs like this are usually long though, so only posting two. They're the kind of things you just sit down and listen to
[video=youtube;8CQurfeAUJc]http://www.youtube.com/watch?v=8CQurfeAUJc[/video]


[video=youtube;PifdG-bH4PQ]http://www.youtube.com/watch?v=PifdG-bH4PQ[/video]

Seriously long. Stuff you lay and sleep with to just absorb.