What the crap is Concept Art?

So a lot of people ask me what I plan to do with Illustration.
I say, "I want to be a concept artist for films."
Usually, the response I get is either a confused smile and nod, or they say,
"What the crap is that?"

So my friends, welcome to my world.

Here is an awesome but random selection of concept art from some recent films.
Try to guess what movie they're from.
(Answers are at the bottom.)

top: tangled
monsters inc
lord of the rings
king's speech
howl's moving castle
alice and wonderland