G-code is a language used to describe the movement of a tool. I think the first uses were for cutting tools, like CNC lathes and milling machines. It describes

G-code is a language used to describe the movement of a tool. I think the first uses were for cutting tools, like CNC lathes and milling machines. It describes things like movements of a tool on linear or rotational axis, cutting tool rotational speed, operation of auxiliary equipment (heater on/off), etc.