I actually took a chocolate class at the Cordon Bleu in Canada. We learned that there are percentages of cocoa and also cocoa butter that has to be present in the various kinds of chocolate. The dark chocolate has the least sugar, milk and other fillers. Dark cocoa has a lot of iron and vitamins. The Spice House in Milwaukee used to carry an "Ebony Cocoa" from Africa, which was PACKED with vitamins, but I think it's hard for them to get a hold of it. Many diet doctors recommend one perfect square of dark chocolate as as treat.