RGB colour mixing involves combining red, green and blue lamps to make different colours; the initial letters of the three primary colours give the process its name. RGB colour mixing is particularly suitable for decorative lighting which changes colour.

In many cases, an additional white light source is used (RGBW colour mixing) to produce a better white light colour. RGB mixing is the principle used to produce white light with LEDs. Fluorescent lamps for this application are identified as RGB lamps.