Herself’s Webtools

The primary colors are red, blue, and yellow when you are working with pigments. From these, plus black and white, all other colors can be made. When you work on your computer you are mixing light. The light primary colors are red, green, blue. From these all the colors you see on your computer screen are made.

Living Color, from Wired Magazine

Terminology

Primary colors — are red, yellow, blue.
Secondary colors — are a mix of two primary colors orange, green, purple.
Tertiary colors — are one primary and one secondary, red-orange, yellow-orange, etc.
Analogous colors — are adjacent on the color wheel (red/orange, red/purple, blue/green etc)
Monochrome — is all one color, usually with different tints, Tones, and Shades.
Contrasting colors — are any of (dark vs light; primary colored (r,y,b); or green, orange, purple)
Cool colors — are green, purple, and blue.
Warm colors — are red, yellow, orange.
Hue — is the amount of color.
Tint — is the amount of white.
Tone — is the amount of grey.
Shade — is the amount of black.

Things to think about when you are choosing colors for your web site:

A Monochrome site feels unified and relaxed.

Complementary colored sites grab your attention.

Contrasting color sites feel balanced.

Bright colors and warm colors accent information, use in small amounts.

Dark and cool colors send things to the background, use for large areas like backgrounds.

Colors

Blue: A soothing color, often evokes feelings of trust. It feels calm, cool, authoritarian, and sad.

Purple: A difficult color to use well. Often it just appears garish. Done properly it can remind you of royalty, magic, and mysticism.

Green: More peaceful than blue and is believed to calm the nerves. it easily blends with other colors and is the easiest to focus on.

Orange: Intense and hot, orange does not tone down well, use it purely and sparingly. It reminds us of fire, energy, it grabs attention.

Red: Is equated with energy and passion. It appears to advance forward, (like all warm colors) it feels cozy, or can signal danger, anger, or heat.

Yellow: Sends a warm glow, like the sun. A happy color, it feels intuitive, and bright. It can also be used to signal caution.

Useful Tools:
Color Scheme Generator 2
Color Schemer Online
Colors on the Web
HTML Color Combination Chooser