The color wheel is useful to designers and illustrators in at least a couple of really important ways. For one thing, it reminds us there are three primary colors, and that when primary colors are mixed, you get secondary colors. When primary and secondary colors are mixed, you get tertiaries. Another way that the color wheel helps designers and illustrators is by helping us brainstorm for ways of coming up with good-looking color schemes. How so? Well they serve as schematics that conveniently highlight different ways of combining colors. Let me show you what I mean.