For an extensive glossary, consult the additional reference at the bottom of the page. Channel is a term used in RGB or CMYK images and can be manipulated with programs like Photoshop.
Channels store the color information in an image.
RGB images contain a composite channel consisting of the red, green, and blue channels. Another channel type, the alpha channel, can isolate particular parts of an image for manipulation and editing. Transparency can be associated with alpha channels. These numbers refer to the binary exponent resulting in the maximum number of colors. It is easier to refer to these different bit depths as modes.