G-code is the instruction language that tells CNC machines and 3D printers where to move, how fast to move, when to extrude or cut, and which tools or temperatures to use. Unlike a CAD model, which describes shape, G-code describes execution: the exact path the machine will follow layer by layer or pass by pass.
In cyber security, G-code matters because it is the last digital step before a physical object is made. If an attacker alters a print job or machine file, they may change dimensions, introduce weak points, waste material, or cause operational failure. Defenders can render, review, and compare G-code to detect unexpected toolpaths, missing layers, or suspicious parameter changes. Checking G-code is a practical control for integrity, quality assurance, and tamper detection in additive manufacturing and CNC workflows.