Blue is one of the tree primary colors of pigments.
What are the other primary color pigments?
The RGB color model is made up of red, green and blue light.
What else do you know about the light spectrum?
electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors.
RGB is a "device-dependent" color model: different devices detect or reproduce a given RGB value differently, since the color elements (such as phosphors or dyes) and their response to the individual R, G, and B levels vary from manufacturer to manufacturer, or even in the same device over time. Thus an RGB value does not define the same "color" across devices without some
darker color. This is called subtractive color-mixing, as mixing pigments subtracts wavelengths from the light that is reflected.
Subtractive secondaries Printing (CMYK).
The mixture of equal amounts of these colors produce the secondary colors red, blue, and "lime" green (the RGB primary colors of light), as follows:
That is, the primary and secondary CMY colors (with secondary colors in boldface) are: 
Ideally, combining three perfect primary colors in equal amounts would produce black, but this