Complementary colour scheme
Colours directly opposite each other are deemed to be visually interesting when used together. While such a scheme is known as the complementary colour scheme, the term is misleading as rather than complementary, the effectiveness of such a scheme is based on contrast.
Split complementary colour scheme
A similar scheme or variation on this would be the split complementary colour scheme where a main colour is selected and used with a further two colours adjacent to it, also delivering strong contrast with some subtlety.
Analogous colour scheme
An analogous colour scheme uses colours that are next to each other on the colour wheel. As contrast is low, it is imperative to clearly demarcate the different colours used. Typically, in such a scheme, there would be a main colour, a secondary colour and an accent colour.
Triadic colour scheme
A triadic colour scheme uses colours spaced evenly around the colour wheel and results in a vibrant scheme. A main colour should be seleted to dominate and further colours used as accents.
Tetradic colour scheme
A tetradic colour scheme is represented by a rectangle with four corners identifying four colours, arranged into complementary pairs. A single main colour is best used, supported by the other colours.
Square colour scheme
Finally, a square colour scheme is similar to the tetradic scheme but all four colours are spaced evenly around the colour circle. As with all colour schemes, the best results are achieved when one colour is dominant.