G-code is a programming language used to control CNC (Computer Numerical Control) machines. It consists of a series of commands that tell the machine how to move, what speed to use, and what tools to employ. G-code is essential for automating tasks in manufacturing, such as cutting, milling, and 3D printing. Each command in G-code starts with a letter, typically "G" for general commands or "M" for miscellaneous functions. For example, G01 indicates a linear movement, while M03 starts the spindle. Understanding G-code allows operators to create precise and efficient machining processes.