In the RGB color space:
R stands for Red.
G stands for Green.
B stands for Blue.
Three numbers (0 - 255) representing Red, Green and Blue can be used to uniquely identify each color in the spectrum.
If Red, Green, and Blue all have the same value, the resulting color is a shade of gray. Black is the absence of all color, or Red, Green, and Blue values are all zero, while White is the presence of the maximum amount of all three component colors, or Red, Green, and Blue all have a value of 255. The RGB model is additive, or light is added to create colors. This means that as the component color values increase, the resulting color becomes brighter.