How Bump Mapping Works

The Chef writes: "Tweak3D has a pretty good article explaining how bump mapping works with 3D accelerated video cards. They cover all the basics of bump mapping and the advantages and disadvantages of several methods. Now if someone asks me how per-pixel shading or environment mapped bump mapping works, I'll have an answer (but I'm not sure if that's a good thing)." With the introduction of the new graphics cards, this is some interesting reading.