The colour wheel is a visual representation of the colour spectrum displayed as a circle. This is the basis of modern day colour theory.

Color theory addresses only the hue component of pure colors. In other
words, it does not take into account the lightness and saturation
components of your colour scheme.
|
Monochromatic Color Scheme: This colour scheme uses only one colour in its variations
of lightness and saturation. |
|
|
|
Analogous Color Scheme: This colour scheme uses colors that are adjacent to each other on the colour wheel. One colour is dominant while the other colours are used to enhance the scheme. |
|
Complementary Color Scheme: This colour scheme uses two colours on opposite side of the colour wheel to create high contrast. |
|
|
|
Split Complementary Color Scheme: This colour scheme uses a colour and the two colours adjacent to its complementary. This is a less strong contrasting colour scheme.
|
|
Triadic Color Scheme: This colour scheme uses three colours equally spaced around the colour wheel. It is used to create colour richness and balance.
|
|
|
|
Tetradic Color Scheme: This colour scheme uses two complementary color pairs. The result appears chaotic but catches attention.
|
You can see from the above that when colours close together on the colour wheel are used, the result is a harmonious presentation that is soothing to the eye. Whereas when colours on the opposite sides of the colour wheel are used, this produces varying degrees of contrast and richness in the end product. And a chaotic arrangement can be used for attracting attention.