Turning a design into controlled machine movements.
A starting point
CNC means computer numerical control. A controller guides a machine along programmed paths. In milling or turning, a tool removes material until the intended shape remains. The program specifies movements and process settings; the machine, tooling and setup determine how those instructions become a real part.
The usual path is CAD geometry, CAM toolpaths, machine-specific program output, then setup and machining. CAM means computer-aided manufacturing. Tool diameter, feed, speed, workholding and the work coordinate origin all matter. Simulation and a checked first run help compare the programmed path with the actual setup.