Spaced at even thirds on the color wheel are blue, red, and yellow - the primary colors of pigment. These are the building blocks of color: they cannot be broken down into other colors, as green can, nor can any other colors combine to create them. Therefore, these three represent the legs on which the rest of the color wheel stands. However, the primary colors of pigment and the primary colors of light are different. The primary colors of light are red, blue, and green, and their properties are quite different. For example, the mixing of red and green light produced shades of yellow and orange, while the same two colors in pigment create brown. (This model for the primary colors is used for television and computer screens, while the primary colors of pigment are used in reference to visual art.)
In between each of the primary colors lies the shade created by the combination of the two. Blue and yellow create green, yellow and red create orange, and red and blue create violet. These combinations are, in turn, known as the secondary colors. It is next to these colors that the primary colors become most vibrant. The primary colors are complemented by the secondary color, which they have no hand in making. Therefore, the complement of blue is orange (and so on). In addition, the combination of blue and orange (and all other color complements) creates brown. The tertiary colors follow, created by mixing one secondary color and one primary color (yellow green, for example). They lie between their respective primary and secondary colors, and directly across from their complements, as with the rest of the color wheel.
There is, of course, a use for such knowledge outside of the color wheel. However, it is with the color wheel that we discover the complements and thus the neutralizers of colors. With this knowledge, we can apply it to the aesthetics of our everyday lives. For example, we now know that the best way to neutralize something with a red hue is to complement it with something green. This idea, when applied to getting dressed, can help to lessen the appearance of ruddy scars or acne. Conversely, a brilliant way to make green eyes sparkle is to wear something red. Decorators also utilize these findings in their trade. A great way to make pale yellow cushions pop, for instance, is to pair them with dusky violet hues. However, another element to consider is that of color harmony. Pairing cyan with orange makes the view reject the combination as being too vibrant to appear attractive. Therefore, the laws of color harmony must be enacted. "Harmonious colors" fall side-by-side on the color wheel, such as blue, viridian and green. When used together, these three colors create a calming effect and play off each other in a harmonious fashion. Hence, "matching" colors tend to bring out their shared base and appear pleasing to the eye.