Chocolate is created by a long process that culminates in the grinding and milling of cocoa beans (or nibs) to produce cocoa solids and cocoa butter. The cocoa butter and cocoa solids are them mixed with milk, sugar, and other flavoring components to get the desired taste. The definition of chocolate caries based on the government and country (with lobbying groups constantly trying to reshape these definitions). In the US, dark chocolate contains must contain at least 35% chocolate liquor (the liquid formed by combining cocoa solids and cocoa butter) and milk chocolates must contain at least 10% chocolate liquor.
Cocoa butter is a type of vegetable oil that is primarily derived from stearic and palmitic acid. Cocoa butter is primarily composed of saturated fats, so it is solid at room temperature. Many chocolate manufacturers attempt to substitute other vegetable oils for cocoa butter, although this is technically not allowed in the US. To get around this the nomenclature “chocolatey” or “made with chocolate” is used.
Cocoa solids are the mixture of the substances remaining after the cocoa butter is extracted. It contains many substances such as the stimulants caffeine and theobromine. Cocoa solids contain many flavonoids, but Dutch process cocoa powder have a much reduced flavonoid concentration. The most common term for cocoa solids is cocoa powder, which can be purchased at most supermarkets.