Physical Properties of Color

Hue:
The name of a color; the property that refers to its position on the color wheel.

Intensity:
Saturation or Chroma which refers to the quality of light distinguishing a brighter tone of a color from a duller one of the same hue. Adding white increases the intensity, adding black diminishes the intensity, adding grey varies the intensity, and adding a complementary hue diminishes intensity.
Value:
The lightness or darkness of the hue in relation to another through the addition of black or white: adding white lightens the color and produces a tint; adding black darkens the color.
Primary Colors:

Red, blue and yellow--these colors cannot be created from mixtures of other colors, but can be mixed to form all other colors.
Secondary Colors:

Color mixtures made from the primaries:

yellow + red = orange

yellow + blue = green

blue + red = violet
Complementary

Hues directly opposite each other on the color wheel: blue and orange, yellow and blue-violet; red and blue-green; green and red-violet; etc.
Tertiary
Six colors created by mixture of a primary color and its adjacent secondary: blue and green make blue-green; red and violet make red-violet; yellow and orange make yellow-orange; blue and violet make|blue-violet; red and orange make red-orange; yellow and green make yellow green.

Color Relationships

Monochromatic:
A color scheme involving the use of only one hue which can vary in values of light and dark.

Analogous
A color scheme which combines several hues that sit next to each other on the color wheel and can vary in value (i.e.: yellow, yellow-green, green, green-blue).

Split Complementary:
A color scheme using one color and the two colors adjacent to its complement.

Triadic:
Involves three hues equally spaced on the color wheel, such as orange, green and violet.

Color Discord:
Purposeful juxtaposition of colors to create a negative reaction or even a feeling of vibration; typically achieved through paring of colors which are widely separated on the color wheel but not complements (such as orange and red-purple).

Uses of Color
To Create Balance:

Color can be used effectively to create a visual asymmetric balance.		 To Create Space:

Colors have an advancing or receding quality: intense, warm colors (red, yellow, orange) and bright values come forward: cool colors (blue, green, purple) and darker values recede. Colors also become less intense as visual depth is implied.
To Create Mood:

Darker, less intense colors create a somber atmosphere while brighter and lighter colors create gaiety.		 To Create Symbolism:

Colors symbolize abstract concepts or ideas, mental or conceptual qualities such as fidelity, sin, innocence or cowardice. Color references however are arbitrary and based in the context of culture.
To Express Emotion:

Yellows, oranges and reds give a feeling of expressed emotion like anger or happiness; cooler blues and greens are associated with quieter feelings or even melancholy.