I`ve been looking this up for years now, and I finally noticed some of you have shown an interest in it. I cant talk much right now, but this picture
and these three links pretty much explain everything. ...I may be a newb....but I`m a damn good info hunting newb.
Check out Howstuffworks(in my opinion, the best of the three, lol)
, or the Institute of Soldier Nanotechnologies