Phong shading
A shading method that interpolates surface normals per pixel and so captures highlights in the middle of a polygon — unlike Gouraud.
Bui Tuong Phong described the technique in 1973 at the University of Utah. Instead of computing the light at the vertices and blending the colours across the surface — as Gouraud shading does — Phong interpolates the normal vectors themselves and recomputes the lighting at every pixel.
The difference shows most on specular highlights: a glint that falls inside a polygon vanishes entirely with Gouraud but is rendered by Phong. The cost is more arithmetic per pixel. The demoscene faked the same glossy look in real time with lookup tables and phony normals long before graphics cards could do it for real.