system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are the primary colors of pigment red, blue, and *yellow* when the primary colors of light are red, blue, and green?
gpt
Pigments are called subtractive. If you mix those three, you get darker colors, supposed to be black in a perfect world. Red, green, and blue are additive, they add up to white. RGB are the primary colors of light, RYB are the primary colors of some pigments. There's also CYMK for printing, and it's another subtractive system. 

Why you get white for RGB has to do with white light being comprised of all colors. Where as pigment absorbs and reflects light, it doesn't emit it. So that's how your mixing is done, through absorption. The more colors you add, the more light that's absorbed, the closer to black you get. Black = all colors absorbed.