Color wheel

A color wheel arranges hues in a circle so you can see how they relate. Isaac Newton drew an early version in his book Opticks (1704) by joining the two ends of the visible spectrum into a loop.

The wheel most designers use has 12 hues: 3 primary, 3 secondary and 6 tertiary. Neighboring colors tend to blend calmly; colors on opposite sides create strong contrast.

There are two families of wheels. Screens mix light, with red, green and blue as primaries; print mixes ink, with cyan, magenta and yellow. Pro tip: the wheel suggests combinations, but always check that text stays readable on its background.