Linked from
The 20 pages that link to Additive color, each with the reason it gives.
Color theoryRelated: Screens combine light rather than pigments to produce colors.
Primary colorsRelated: Red, green, and blue light are primaries in the standard additive system.
Color modelRelated: RGB models encode this mixing process, unlike models for reflective inks.
HWB color modelRelated: HWB ultimately specifies colors intended for screen-based light emission.