Color measurement systems
Munsell and Ostwald and Lovibond, oh my, and RGB,
L*a* b or tristimulus (Hunter Lab).
These are methods of measuring color. There are a lot. You might want to describe the RGB or the tristimulus method, both are based on the eye.
http://www.hunterlab.com/pdf/color.pdf
This is a long power point explanation of the tristimulus and L*a* b color methods.
The human eye has three color sensors, mainly Red, Green, and Blue. If you were a computer programmer you would use the RGB system to specify a color for computers. 255-0-0 or FF0000 is red, 0-255-0 or 00FF00 is green, and 0-0-255 or 0000FF is blue. 0-0-0 or 000000 is black and 255-255-255 or FFFFFF is white. Color screens only have red, green, and blue pixels but mixing these colors allows more than 16 million possible colors!
Tristimulus method takes account of the light source (sunlight nearly white, fluorescent is greenish), eye sensitivity (green/yellow is max), and the actual reflectance spectrum of the object to provide a color value with three numbers. What is amusing to me, as a scientist, the eye sensitivity is mostly based on small panels of people, but this method of measuring color is one of the best. One panel of about 20 people in the 1930's was the eye sensitivity standard for about 50 to 60 years.
The Hunter L*a* b method provides 3D coordinates to plot a color. That becomes much more complicated.
The reference site above is an excellent lecture on color and expanation of the system. You don't need to understand the equations in the L*a* b second half, the slides do a very good job.
You might also compare the first three, all based upon comparing a color to standard color samples on cards or glass. Or stick with the RGB system, next most complicated, and not very.
Best to you