What is a CNC Machine?
A CNC machine uses computer controlled motion along multiple axes, normally at least two (X and Y), and a tool spindle that moves in the Z (depth). The position of the tool is driven by direct-drive stepper motor or servo motors in order to provide highly accurate movements.
There are multiple types of CNC machines on the market, but the most common types are Mills and Lathes.
Both types of machines use computer controller motors to move a tool to a specific XYZ coordinate to start an material removal process that produces a highly dimensionally accurate part.