Why is purple not a color of the rainbow? Do we need indigo and violet?

Question

Basically what the title asks.

All the other colors of the rainbow are either primary or secondary. Violet is a shade of purple and (as I’ve always understood it) indigo is somewhere between navy and purple.

In: Other

Answer 1

Purple doesn’t actually exist on the visible light spectrum at all—it’s made up by our minds. Violet does actually exist on the light spectrum.