G-Code (aka RS-274)

A standardized-but-not-very (think HTML extensions) language for machine tools.

Originating at MIT in the 1950 era, standardized in the United States by the Electronic Industries Alliance in the early 1960s. Final revision in 1980 as RS-274-D.

Other countries use ISO6983, DIN66025, PN-73M-55256, PN-93M-55251. Manufacturers often extend the G-Code with proprietary settings.  Siemens and Fanuc were popular controllers used.

CAM programs will often feature post-processors, which turn the CAM specific toolpaths generated into machine specific G-Code language.

Finally, some machines are doing away with G-Code via conversational programming.