HDRI Explanation?
 

Well, I used HDRI in one of the tutorials that I completed, but I still can't totally understand what they do. Do they add the illusion of a scene, or take the lighting from a scene and put it into the 3d scene? If anyone could explain how HDRI's work, or link me to a website that does, I would really appreciate it.

Yeah sure mate,

"In computer graphics and cinematography, high dynamic range imaging (HDRI for short) is a set of techniques that allow a far greater dynamic range of exposures than normal digital imaging techniques. The intention is to accurately represent the wide range of intensity levels found in real scenes, ranging from direct sunlight to the deepest shadows. "