The FDA established rules for labeling white chocolate which went into effect on January 1, 2004. The rule states that a product labeled and marketed as white chocolate must contain at least 20 percent cocoa fat, 14 percent milk solids and 3.5 percent milk fat, and not more than 55 percent sugar (or other nutritive carbohydrate sweetener).
White chocolate originates from the cocoa (cacao) plant, but it is not 'chocolate.' According to the FDA, to be called 'chocolate' a product must contain chocolate liquor, which is what gives it the biter intense chocolate flavor (and color) to dark and milk chocolates.
White chocolate contains cocoa butter, milk solids, sugar, lecithin and flavorings (usually including vanilla). Cocoa butter is the fat from cocoa beans, extracted from the cocoa beans during the process of making chocolate and cocoa powder. Cocoa butter has very little 'chocolate' flavor.
Cocoa butter is one of the ingredients used to make real chocolate, it is gives chocolate the ability to remain solid at room temperature, yet melt easily in the mouth.
Cocoa butter is one of the most stable fats known, containing natural antioxidants that prevent rancidity and give it a storage life of 2 to 5 years. It is used for its smooth texture in foods (including chocolate) and in cosmetics and soaps.
Although there is not yet a formal definition, white chocolate contains cocoa butter but no non-fat cocoa solids. Mostly used as a coating, it contains sugar, cocoa butter, milk solids and flavorings. Not really "chocolate" since no chocolate solids other than cocoa butter are present. Sweet, milky dairy flavor with a hint of chocolate from the cocoa butter. Color ranges from pure white to yellow-white. Used for candy bars; baking chips; bakery coating.
National Confectioners Association & Chocolate Manufacturers Association