CNC technology has been around since the 1940s, when a CNC mill was first controlled by an analog computer. That system gradually gave way to an all-electronic control via a computerised code, which eventually led to the digital control used today.
CNC literally stands for Computer Numerical Control, meaning that the physical movements of the machine (milling, drilling and cutting) are controlled by a computer via a complex mathematical coordination system. Its main functions are to cut, engrave and carve objects out, essentially a replacement for the usual hand-held router. By introducing computer control to the process, the number of potential errors or miscalculations is dramatically decreased.
A computer moves the router or spindle on the CNC in 3 different directions (aka axes) to cut out different materials such as wood, composites, aluminium, steel, plastics, glass, and foams to a pre-determined shape from a digital file. There is the X axis (which always moves from side to side as you face the machine,) the Y axis (which always moves from front to rear as you face the machine,) and the Z axis (which always moves up and down.)