Color concepts:

Complementary colors, or contrasting colors, lie opposite each other on the color wheel, like yellow and purple. When used together, they have a striking appearance.

Analogous colors lie next to each other on the color wheel, like yellow and orange; using them together has a more harmonious effect.

However, the colors you use in your design palette may contain both complementary and analogous colors, like a scheme using purple, green, and yellow.

A room’s “palette” is the two or more colors used consistently throughout its design. A neutral palette would use colors like eggshell, brown, and grey; a warm palette would use reds, yellows, and oranges; and a cool palette would use greens, blues, and purples. A bold palette uses bright or dark colors, and a light palette uses whites and pastels.

Dark colors will make a space seem smaller, while light colors will make a space seem bigger.

Things to consider when you pick out a color for your carpet:

Other design elements in the room. Good interior design is about balance, so whatever color you choose for your carpet, make sure it balances well with your furniture, walls, and drapes. A room with bright yellow walls and red drapes, for example, should have a carpet with a neutral tone, like white, tan, brown, or grey. But if a room has white walls and understated furniture, you might consider using a bold carpet to add interest and bring out some of the colors in, say, the flower pattern in your drapes.

How much light the room gets. A room that gets a lot of strong sunlight during the day should have a palette of light colors to preserve the room’s bright, airy feel, and conversely, a dimly lit room should have a darker palette.

How high the ceiling is. A dark, bold carpet would make a room with a low ceiling feel stuffy but would serve as an excellent grounding factor in a room with a high ceiling.

For more on color theory:

“Color Theory” by Color Matters. http://www.colormatters.com/colortheory.html

For examples of how your carpet can interact with the other elements of design in a room:

“Rugs & Carpets” by Architectural Digest. http://www.architecturaldigest.com/resources/features/2009/02/rugs_slideshow?showall=true

“Living Room Flooring Ideas” by Better Homes and Gardens.
http://www.remodelingcenter.com/flooring/living-room-floor-ideas/?catref=rem49&slideid=/templatedata/remodel/slideshow/data/1220017451660.xml&page=1