All-wheel drive and four-wheel drive explained

Winter's here and, like clockwork, everyone's started driving like idiots.
If you recently bought a vehicle with part-time four wheel drive, four wheel drive, all wheel drive or anything else in between, this might be a good time to brush up on what your ride's good for and what you should avoid. Look no further than this video. Unless you really want to. If so, you'd do well to spend some time reading this story by Jalopnik.