Blender uses the model additive Light color treatment.
Therefore used three “channels” (RGB ,Red, Green, Blue) with primary colors.
There is another model, complementary to the previous, which is used to study painting, and you can experiment by mixing the colors of the clay, painting etc.; subtracts each color that reflects the colors, so that adding new colors “off” and obscure.
This second model is called “subtractive” and in principle has no interest in creating synthetic images, although their study may reinforce and complement the colors by adding.
In both cases, any color can be obtained by mixing three of them denominated “primaries”.
Two very comprehensive references, in Spanish or English, are developed in wikipedia:
The impact on a surface the different lights, components are added (adding colors) to form the resulting color.
The sum of the three primary colors give the white on the black model in additive and subtractive.
The sum of two primary colors can obtain so-called secondary colors.
To be able to handle with ease lighting in image editing programs, and in the generation of animations such as Blender, must have a high understanding of the additive model.
I suggest reviewing the proposed links before continuing with our study of light, facilitating their understanding and mastery in lighting exercises.
Slight variations in some of the classic images used to illustrate these models (see top image) you can see below: