Normal Mapping in Blender
Normal mapping is quite possibly THE coolest thing I have ever done in Blender. I absolutely love it. I just can’t describe how awesome it is. But I did come up with a decent way to help one visualize it.
Imagine you have a regular piece of white printer paper as well as a pencil at your disposal. You sit down and scratch out a decent, well shaded drawing of whatever you like, say, a house, for example. Now, that well shaded house has light and dark sections that make it look much more realistic than if it were just a two tone sketch, right?
Now imagine that when you hold the paper in front of your face and turn it left and right, the shading changes! As if it were a 3d object, the ‘lighting’ of the scene you scribbled on paper magically changes, and it’s only a drawing, on a flat piece of paper! I know it’s not perfect, but that is in a sense a good visual way to describe what Normal Mapping can accomplish, at least in the case I am describing.
This video depicts a flat plane. Four corners, and a image mapped to it. That’s it. There is no high level of physical detail, no bumps to make the light shine differently. But it sure looks like it, doesn’t it. 
Here’s the blend file if you want to see for yourself, or play around with normal mapping. The texture and tutorial I followed to get the concept down can be found at tutorialsforblender.com
–Lace