CNC is the automation of machine tools that are operated by precisely programmed commands controlled by a computer, as opposed to controlled manually by hand wheels or levers, or mechanically automated by cams alone.
In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine by a post processor, and then loaded into the CNC machines for production.
CNC mills use computer controls to cut different materials. They are able to translate programs consisting of specific numbers and letters to move the spindle(or workpiece) to various locations and depths. Many use G-code, which is a standardized programming language that many CNC machines understand,