In 1975, mathematician Bui-Tuong Phong proposed a simple reflection mathematical model to improve upon the shading models in use at that time. In addition to the simple shading model, Phong proposed a new algorithm to average the shading on polygonal representations of smooth surfaces that recovered the smooth appearance of the original surface.

The Phong algorithm provided a significant improvement over Gouraud shading, an averaging algorithm that greatly enhanced the smooth appearance of polygonal surfaces. The success of the Phong shading model rests on what could be called the principle of 'model authenticity'. This principle was summarised by Phong as:

"In order to successfully simulate some process of nature, any model must recognise and successfully simulate the natural laws by which the process occurs."

Since Phong first came up with the algorithm, it has been refined and re-interpreted and applied in numerous ways, but it still remains one of the main techniques used in 3D polygon games to give the polygons a more realistic appearance. And you thought it was all paper and glue, didn't you, eh?