Complementary colors are pairs of colors which, when combined in the right proportions, produce white or black. When placed next to each other, they create the strongest contrast and reinforce each other. They are widely used in art and design. The pairs of complementary colors vary depending upon the color model, and how the color is made. In painting, which uses subtractive colors, the traditional primary–secondary complementary color pairs, described since at least the early 18th century, were red–green, yellow–violet, and blue–orange.