A color wheel is a tool used by designers and artists to make decisions about different hues and their juxtaposition. The wheel shows the rainbow of the visible spectrum and makes it easy to tell, at a glance, which shades coexist harmoniously and what options will enliven a room's decor. You can use the color wheel to decide on the palette for a room or for the entire house, the dominant colors for a new carpet, or the best shade for drapes to go with your inherited antique sofa.

Colorful interior
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Use a color wheel to pretest surprising color combinations.

Easy as 1-2-3

Colors can be grouped into primary, secondary and tertiary hues. Primary colors -- red, yellow, and blue -- are not mixes of any other colors. They exist as original pigments from which all other colors are derived. Secondary colors are blends of two primaries: orange is red and yellow; green is yellow and blue; violet is blue and red. Tertiary colors are a mix of one primary and one secondary color, usually in a ratio of 2 to 1. Red-orange, red-purple, yellow-orange, yellow-green, blue-purple and blue-green are the six tertiary colors.

Color Theory and Your Throw Pillows

You can change the look of a room with decorative pillows, a carpet, a couple of lampshades. When you understand basic color theory, you have a shortcut to achieving the results you want. Vibrant harmony and serene harmony are all about choosing relationships on the color wheel. Color complements are direct opposites on the wheel. Red is the complement of green; blue is the complement of orange; yellow is the complement of purple. They work well together, and they are dynamic. Analogous colors are three hues that exist side-by-side on a simple 12-color wheel. One of the colors is typically predominant -- blue-green, blue and blue-purple are analogous and strongly related. Monochromatic colors are varying intensities of the same hue. A good example is a paint color strip -- those different shades are all the same color in gradients from deeper to lighter.

Pick Your Palette

Play with the color wheel when choosing paint, trim, upholstery fabric, rugs and accessories. Pay attention to the warm and cool light from different bulbs and how it affects the colors in a space. Use a mix of monochromatic neutrals and textures for a spare but rich room, and triadic colors for an extra jolt of excitement that doesn't clash. Triads are three colors equidistant on the color wheel -- basic red, yellow and blue; or tertiary yellow-green, blue-violet and red-orange, for example. An ombre treatment in a little girl's bedroom might use saturations of red into pink from raspberry to blush-white -- monochrome but far from boring. The dining room with a pumpkin-colored accent wall could handle the contrast of a gleaming teal sideboard if the rest of the room is limited to white, black and gray.

Some Like It Hot

Don't overlook color temperature when deciding on decor. Colors on the red side of the light spectrum -- red to yellow-green -- are warm and seem to advance or close in a space. The other side of the spectrum -- from green to red-violet -- is cool and appears to expand a space. But temperature is a complex game, and both green and violet switch between advancing and receding in relation to the colors they are near. Both can be used as neutrals. In general, aim to keep the colors in one area or room either warm or cool -- a white wall paint with a lot of yellow, which is creamy and warm, won't coexist gracefully with a cool blue sofa. A slightly grayed cool white would be better, and the lighting should avoid any hint of yellow, which would muddy the colors.