What programming language do 3D printers use?

Most 3D printers use .STL, or an AMF program. The first step is to have a design of an object done in a CAD program, any CAD program is fine. Then the CAD program is translated into instructions that a 3D printer can use through .STL or AMF, or something similar. read more

You'll need to clarify. If you mean what languages run on the computer chips which drive the motors and extruder, its usually processing (C derivative common on but not limited to arduino). read more

Today, many desktop 3D printers use a numerically controlled programming language made up of a series of commands called G-Code. Most of these commands start with a G (hence the name), but there are also some common machine-specific codes that start with an M. read more