What is the definition of Computer Numerical Control (CNC)?

The definition of Computer Numerical Control (CNC) refers to a method of operating machine tools through the use of computer systems and programmed instructions. This technology automates the control of machining tools by utilizing software, allowing for precise and consistent manufacturing processes. CNC systems read a computer program composed of a specific set of instructions, which dictate how a machine should move and operate. This advanced form of automation improves efficiency, accuracy, and complexity in manufacturing tasks compared to manual control systems.

The other options do not accurately capture the essence of CNC. A manual control system for machines is outdated in the context of what CNC offers, as it relies on human intervention for operation. Physical hardware for cutting pertains to the machines themselves, but does not encompass the control method utilized. Finally, a technique for welding metals does not relate to CNC, as it primarily concerns machining operations rather than joining methods. Thus, the emphasis on utilizing computers and programs highlights why the second choice is the appropriate answer.