Color is an important element in design that can affect how a design looks and feels. There are several color models used in design, with RGB and CMYK being most common. A color scheme refers to the combination of colors used in a design. Common color schemes include monochromatic using one hue, analogous using adjacent hues, complementary using opposite hues, split-complementary, achromatic using black, white and grays, and triadic using three evenly spaced hues. The use of different color schemes and an understanding of color theory allows for purposeful use of color in design.