Adjacent colors are colors that are next to each other on the color wheel. In the context of color theory, the six adjacent colors form a hexagon on the wheel. These colors include red-violet, red, red-orange, yellow-orange, yellow-green, and green. Each of these pairs of adjacent colors share one color attribute (either hue, saturation, or value) but differ in the other two. Understanding adjacent colors is important in design, art, and fashion as it helps create harmonious color combinations.