system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do computers use Red, Green, and Blue (RGB) instead of the three primary colors, Red, Yellow, and Blue?
gpt
The difference is between additive and subtractive colors.  When adding more of the color source makes the result brighter, usually from emitting light sources like light bulbs, LEDs (computer monitors), the sun, the primary colors are RBG.  When all additive primary colors are present you get white. 

When adding more of the source makes things darker, like paints, and other light absorbing/reflecting scenarios, the primary colors are subtractive and you get RYB.  All subtractive primary colors make black.