The RGB Color Model

All visible colors can be obtained by combining red, green, and blue light. The red/green/blue (RGB) color model takes advantage of this fact.
The RGB color model, depicted as a cube in Cartesian three-dimensional (3D) space

Hue, Saturation, and Brightness

Color, as perceived by the human eye, is a function of the wavelength of optical EM energy. When most of the energy is concentrated near a single wavelength, you see an intense hue. The vividness of a hue is called the saturation. The brightness of a color is a function of how much total energy the light contains. In most video displays, there is a control for adjusting the brightness, also called brilliance.

3D Color

A color palette is obtained by combining pure red, green, and blue in various ratios. Assign each primary color an axis in Cartesian three-dimensional (3D) space as shown in above figure. Call the axes R (for red), G (for green), and B (for blue). Color brightness can range from 0 to 255, or binary