It is an int'l color matching system used by the graphic arts. Each color has a code. I used it for mixing speciality inks for my printing presses. They have pastel guides, metallic, interior..you name. Pantone comes out every year with "colors" of the year for home and fashion.
I believe there is a site where you can print out guides..of course the colors will differ a bit with each printer. Color wheels at the quilt store are alot cheaper.