CNC stands for Computer Numerical Control. Originally, just Numerical Control.
The first NC Machines were constructed based around existing tools that added a motor to move the controls around to specific points, that were fed into the machine via Punched Tape. As time passed these mechanisms were improved upon with Digital and Analog Computers.
After WWII Parsons, one of the original pioneers in NC, was approached by the Air force and partnered with MIT in 1949, to Develop a more accurate CNC machine. MIT Would eventually take over the project and force Parsons out.
In 1955 the MIT Team left to form Concord Controls, Producing a new controller that replaced punched tape with a magnetic tape reader that General Electric was prototyping.
CNC Technology was standardized in the late 1960's, as development was underway to automate making of magnetic tapes.
CNC machines Today use Languages like G-Code to direct the machine to points and speeds, built on advanced micro processor infrastructures. These machines come in multi axis builds and are capable of deliver complete parts in a short amount of time.