Dye-based inks are used predominantly by illustrators and graphic artists for their rich and bright colours that are well suited to reproduction. Once dry, they are no longer water-soluble. Being dye-based they are also not lightfast, meaning they will fade in sunlight.
Pigment-based inks, or watercolour, is made from pigment and a gum arabic binder that remains water-soluble once dried and the colours tend to be more subtle than the dyes. Many modern pigments are described as lightfast and they are considerably more resistant to fading than dyes.
Artworks painted using dye-based inks can be protected from fading with ultra-violet absorbing glass, and will not fade under incandescent light.