A field of mathematics heavily used in 3-D calculations. Since every point in 3-D space has three values, you can represent rotations, movements, and other actions within 3-D space as matrix computations; solving these matrix activities and doing a final projection into 2-D gives you a representation of a 3-D world and objects in 2-D. This is how OpenGL works, why Doom and Quake look like they do, and represents much of the work going on in computer graphics. See SIGGRAPH.