Computerized Numerical Control.  This refers to modern milling machines and other tools that can carve complex parts out of solid material.  CNC can be applied to a wide range of manufacturing processes such as metal cutting, woodworking, water jet cutting, laser cutting, and electrical discharge machining.

My goal with CNC is to build a small to mid-size machine to carry a woodworking router.  It will have 3-axis to start, with a fourth (rotary) axis added later.