My favorite color is blue, it's a great color.
You mean Blue as in one of the three primary colors in the traditional color theory? 
Yes that color blue. It is cool how it's a primary color. There are 3 primary colors right? 
Yes, they are known as color theory. your eye on see's blue light between wavelength between approximately 450 and 495 nanometres. Any thing else and you can not see it. 
I don't know anything about this color theory. Is it based on colors you can see with the human eye? 
Color theory or colour theory is a body of practical guidance to color mixing and the visual effects of a specific color combination.