or with its full name computer numerical control (English: Computer numerical control, CNC), machining tools (such as drills, drilling tools, lathes) and 3D printers are automatically controlled by a computer and the machining process operates on the workpiece to be shaped. A CNC machine processes a specific material-based workpiece (such as metal, plastic, wood, ceramic, or composite) to meet specifications more precisely than manual, by following the instruction programmed with codes, until it is in the desired shape.

A CNC machine is a precision maneuverable platform with multiple motors, controlled by a computer according to its programmed instructions. Programmed instructions are written and sent to a CNC machine in the form of a sequential program of machine control codes such as G-code and M-code, and then the process is started. Instructions can be written by one person or often with computer-aided graphic-design (CAD) software. Again in the case of 3D printers using G-codes, the object to be printed is "sliced" before the instructions are generated.

Controlling the CNC manually (using devices such as handwheels or levers) or mechanically by pre-manufactured pattern guides (cams) is a major improvement over other non-computerized machines. In modern CNC systems, the design and manufacture of a mechanical object is highly automated. The mechanical dimensions of the object are defined using CAD software and then translated into manufacturing directives with computer aided manufacturing (CAM) software. The resulting directives are converted (by "finisher" software) into specific commands required for a particular machine to produce the component, and then loaded into the CNC machine. Modern machines often combine multiple tools into a single "cell", as any one component may require the use of many different tools—drills, saws, etc. Other setups use a range of different machines, with an external controller, human or robotic operators moving the component from machine to machine. In either case, the sequence of steps required to produce any object is fully automatic and produces objects that closely match the original CAD.