What is the G and M code in CNC machines?

G and M codes are the programming languages used in CNC machining to control CNC machine tools. G-codes are primarily used for specifying the movements of the machine, such as linear interpolation, circular movements, and other specific functions related to the actual path of the tool. M-codes, on the other hand, handle machine functions that are not directly related to the path of the tool, such as turning the machine on or off, starting or stopping the spindle, and controlling coolant. Together, G and M codes provide a comprehensive set of instructions that CNC machines follow to produce parts accurately and efficiently.