Complementary (also known as supplementary or contrasting) colors are colors that sit opposite of each other on the Itten color circle. The combination of such colors creates a vivid and energizing effect, especially at maximum saturation.
Your designs can spark a whole range of emotions in people. Color theory unlocks the secrets of how to use hues to inspire joy, sadness, and even hunger. -- or, you know, make art or not to have clashing colors.