What is shading?

Shading in computer graphics refers to the process of altering the color of an object/surface in the 3D scene, based on its lighting environment, surface properties and angles relative to lights and viewers. It is used to add realism and depth to 3D models by simulating how light interacts with surfaces, creating highlights, shadows, and variations in color. Common shading techniques include flat shading, Gouraud shading, Phong shading, and physically based rendering (PBR).