system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does brown not appear in a rainbow (or on a color wheel)?
gpt
Brown isn't a color in its own right. It's a phenomenon of our brain interpreting a certain mix of colors.

Edit: brown can be made from mixing any two colors on opposite ends of the color wheel: yellow and purple, blue and orange, red and green.