A hue circle (also called color wheel or color circle) is a chart of hues around a circle and a method for organizing colors systematically. Differing wavelengths of light are perceived as a continuous spectrum of colors in the following sequence: red, orange, yellow, green, blue, purple. A circular illustration of this sequence is called the hue circle.

A systematic method of notation is required to describe colors accurately. This system for displaying color is called the color order system and can be represented using a hue circle or a color solid. Today, there are several well-known systems such as the Munsell color system, Ostwald color system and PCCS (Practical Color Coordinate System). The Munsell color system consists of 10 hues comprising 5 primary hues (red, yellow, green, blue, purple) and their intermediate hues (yellow-red, yellow-green, blue-green, blue-purple, red-purple). The Ostwald color system, on the other hand, is made up of 8 primary hues (yellow, orange, red, purple, blue, blue-green, green, yellow-green) which are further divided into three groups to form 24 hues. The two colors on the opposite sides of an Ostwald’s hue circle are complementary colors which, when combined, produce achromatic colors.

* The chart shown is only an approximate display of the relationship between colors and is not an accurate recreation. Colors also appear different depending on the viewing environment.