Statistical control (also computer numerical control, and commonly called CNC)[1] is the automated power over machining tools (such as drills, lathes, mills and THREE DIMENSIONAL printers) by means of a computer. A CNC machine processes a item of material (metal, plastic, wood, hard, or composite) to meet specifications by following coded designed instructions and without a manual owner directly controlling the machining operation.

The CNC machine is a motorized maneuverable tool and frequently a motorized maneuverable system, which are both managed by a computer, according to specific input instructions. Instructions are shipped to a COMPUTER NUMERICAL CONTROL machine in the form of a sequential program of machine control instructions such as G-code and M-code, and then executed. This program can be written by a person or, far more often, produced by graphical computer-aided design (CAD) or computer-aided manufacturing (CAM) software. In the situation of 3D ink jet printers, the part to be printed is "sliced" before the instructions (or the program) are produced. 3D printers also use G-Code.

COMPUTER NUMERICAL CONTROL is a huge enhancement over non-computerized engineering that must be manually managed (e. g. using devices such as hands wheels or levers) or mechanically managed by pre-fabricated design guides (see pantograph mill). In modern CNC systems, the design of a mechanical part as well as manufacturing program are quite automated. The part's mechanical dimensions are defined using CAD software and then translated into production directives by computer-aided manufacturing (CAM) software. The resulting assignments are transformed (by "post processor" software) in to the specific instructions essential for a particular machine to create the component and then are packed into the COMPUTER NUMERICAL CONTROL machine.

Since any particular component might require the utilization of several different tools – drills, saws, etc. – modern machines often mix multiple tools into one "cell". Within other installations, several different machines are utilized with an exterior controller and human being or robotic providers that move the component from machine to machine. Within either case, the series of steps required to produce any part is highly automated and produces a part that closely matches the original CAD sketching.