Norma, anodizing is a process where a chemical is used to make the outer surface of the aluminum much harder than normal aluminum. I have a number of regular ( shiny ) aluminum pans, when you use a pie cutter it leaves tracks because the aluminum is so soft. My anodized pans do not have tracks, because the outer layer, though extremely thin, is very hard. The color is added as a dye as part of the anodizing process, but I think they can add any color they want or skip the dye altogether, but even then, the anodizing will change the color of the original metal. Anodizing is much more durable than a nonstick coating, which wears out or can be scratched. OTOH, if you soak an anodized part in ammonia too long, ( many hours ) it can bleach out the dye - whether it removes the hard layer I don't know. For household use, I find the anodizing pretty durable.