Hue

Hue is somewhat synonymous to what we usually refer to as "colors". Red, green, blue, yellow, and orange are a few examples of different hues. The different hues have different wavelenghts in the spectrum.

Value

The value is a measurement of the brightness of a colour. The brighter a colour is, the higher is its value and the more light it emits. For instance, a vivid yellow is brighter than dark blue, therefore its value is higher than that of the blue. A good way to see the difference in the values of colours is to look at the corresponding greyscale version.

Tint and shade

These are terms to describe how a color varies from its original hue. If white is added, the lighter version of the color is called a tint of the color. On the other hand, if black is added the, darker version of the color is called a shade of the color.

Saturation

Saturation can also be called a color's intensity. It is a measurement of how different from pure grey the color is. Saturation is not really a matter of light and dark, but rather how pale or strong the colour is. The saturation of a color is not constant, but it varies depending on the surroundings and what light the color is seen in.

Note: In graphic software such as Adobe Photoshop a conversion to grayscale can be done in different ways - with different results. Changing the color mode to grayscale will preserve the value of the colors, while decreasing the saturation to zero will not.