What does it mean? White light is made up of equal quantities of red, green and blue light: our eyes interpret different mixtures of these primary lights as the sensation of colour. RGB is shorthand for the colour space used in editable Photoshop files.
Stands for: Red, Green, Blue
The three primary components of white light and the visible spectrum, RGB is a framework (or colour space) for analysing and measuring the hue of light sources. There are several ways of calibrating light sources for different purposes, but they all start by defining white light. From this starting point, each framework determines the red, green and blue components according to its structure.
Examples of alternative frameworks to Adobe RGB (default colour space in Photoshop): Hue, Saturation and Brightness (HSB)(eg Microsoft Word); Luminance, a,b (Lab) a very early (interwar) international colour space with a very handy use for lightening pictures in Photoshop.[cue future photoshop levels tutorial]