CNC is an acronym that stands for Computer Numerical Control, and this has been around since the 1970s. Before the 1970s, the same system was simply known as Numerical Control or NC. Computers were introduced into these controls during the 1970s, which is why there was a name change. CNC plays an important role in nearly every form of manufacturing across the globe in some way or another. People that work in manufacturing of any type generally experience CNC in some form or another.
CNC machines are typically designed to replace existing manufacturing machines and processes, or to work in conjunction with them. For example, one of the simplest of all manufacturing processes is to drill holes, which is something that any drill press is capable of doing. A person can set up the drill press, involving setting the speed, securing the drill bit in the drill chuck and so on, or a machine can automate a great deal of the process. There is a great deal of manual intervention involved in many simple manufacturing processes, including simple drilling. The benefit behind a CNC machining process is to greatly simplify the process by allowing a computer to control much of the process for you.
The CNC machine equivalent of a typical drill press can actually be programmed in such a way that the operation is carried out in an automated fashion. Everything that the human drill press operator was responsible for doing by hand can now be managed by a machine, including putting the drill in the spindle, activating that spindle, positioning your work piece beneath the drill, actually machining the hole and then turning the spindle off again. For this reason, many manufacturing companies are adopting the use of CNC machinery because it saves time and labor costs while improving precision.