Wikipedia uses the following description of RGB codes: "The RGB color model is an additive color model in which Red, Green and Blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors: Red, Green and Blue. The main purpose of the RGB color model is for the sensing, representation and display of images in electronic systems, such as televisions and computers." More information on RGB codes can be found on Wikipedia.