The basic color chords based on the color wheel.

 Complementary 

Colors that are opposite each other on the color wheel are considered to be complementary colors (example: red and green).

The high contrast of complementary colors creates a vibrant look especially when used at full saturation. This color scheme must be managed well so it is not jarring.

Complementary colors are tricky to use in large doses, but work well when you want something to stand out.

Complementary colors are really bad for text. 

Split-Complementary

The split-complementary color scheme is a variation of the complementary color scheme. In addition to the base color, it uses the two colors adjacent to its complement.

This color scheme has the same strong visual contrast as the complementary color scheme, but has less tension.

The split-complimentary color scheme is often a good choice for beginners, because it is difficult to mess up.

Triad 

A triadic color scheme uses colors that are evenly spaced around the color wheel.

Triadic color harmonies tend to be quite vibrant, even if you use pale or unsaturated versions of your hues.

To use a triadic harmony successfully, the colors should be carefully balanced - let one color dominate and use the two others for accent.

 Analogous 

Analogous color schemes use colors that are next to each other on the color wheel. They usually match well and create serene and comfortable designs.

Analogous color schemes are often found in nature and are harmonious and pleasing to the eye.

Make sure you have enough contrast when choosing an analogous color scheme.

Choose one color to dominate, a second to support. The third color is used (along with black, white or gray) as an accent.

 Square

The square color scheme is similar to the rectangle, but with all four colors spaced evenly around the color circle.

The square color scheme works best if you let one color be dominant.

You should also pay attention to the balance between warm and cool colors in your design.

Rectangle (tetradic)

The rectangle or tetradic color scheme uses four colors arranged into two complementary pairs.

This rich color scheme offers plenty of possibilities for variation.

The tetradic color scheme works best if you let one color be dominant.

You should also pay attention to the balance between warm and cool colors in your design.