Black is not an individual color of light, but it is a pigment. A black object reflects no visible lightwaves, but the result is still distinct from other colors. For all lay intents and purposes, black and white are both colors.

The "black/white are not colors" argument is pure pedantry. It's just a semantic debate between how you define "color." No, black is not a "color" if you define the word as "lightwaves in the visible spectrum reflected from an object to be interpreted by the human brain via the waves hitting the retina," but I don't think lay people are so picky.