Color is the result of human perception.
Color is one of the most basic elements of design. The use of colors in art has been established to be one of the earliest forms of non-verbal communication, dating back to when cavemen painted their walls with ochre or other natural pigments. The earliest known color-producing method was by grinding a powdery substance, often different colors are mixed together in order to create a desired hue which can be applied to objects for decoration or camouflage.
A complementary color scheme is any group of two colors, one each on opposite sides of an RGB color wheel. When placed next to each other, they appear almost harmonious without any harsh contrast between them while at the same time providing visual interest and producing an effect that is pleasing to the eye.
There are two main types of color models used in graphic design - RGB (Red Green Blue) and HSL (for hue, saturation, lightness). The difference between them is where they get their information from: RGB gets it from light, while HSL gets it from human perception.