Primary colors
The basic colors that can be mixed to make all other colors. The primary colors cannot be made by combining other colors.
Secondary colors
Colors that are made by mixing two adjacent primary colors. For example, red and blue light mixed give magenta light.
Tertiary colors
These colors are created when mixing one secondary and one primary color. i.e. blue + magenta = purple.
Color wheel
Color Wheel - A circular chart of colors from which many color relationships can be derived.
Hue
The color in its purest form, with no black, gray, or white added. For example, scarlet, crimson, and pink have the same hue - red. You can see hues on the outer edge of the color wheel and in the spectrum.
Saturation (chromaticity or color intencity)
Saturation can also be called a color's intensity. It is a measurement of how different from pure gray the color is. Saturation is not really a matter of light and dark, but rather how pale or strong the color is. The saturation of a color is not constant, but it varies depending on the surroundings and what light the color is seen in.
Shades
Shades are mixtures of a hue and black.
Tints
Tints are mixtures of a hue and white.
Tones
A tones is a hue with gray added (tending towards neutrality), or a hue with some strength of its complementary color added.
RGB and HEX
The standard color model used on the Internet is RGB, which consists of a set of three values from 0 (zero) to 255 in decimal notation, or 00 - ff in hexadecimal (frequently mis-spelt as 'hexidecimal') notation. One of these values is for red, one is for green, and one is for blue - thus: #RRGGBB
where RR, GG, BB are the hexadecimal digits specifying the Red, Green, and Blue values of the color. The colors you create depend on the mixture of these three colors, which are indicated by their respective numerical values. Zero indicates the absence of a particular color; 255 indicates the strongest use of a color.
CMYK
Short for Cyan-Magenta-Yellow-Black, and pronounced as separate letters. CMYK is a color model in which all colors are described as a mixture of these four process colors. CMYK is the standard color model used in offset printing for full-color documents. Because such printing uses inks of these four basic colors, it is often called four-color printing.