All types of chocolate use material derived from cacao, the fruit of the tropical Theobroma cacao tree. There are three basic types of chocolate: dark, milk, and white chocolates. Over the years, some have tried to create other types of chocolate. Recent examples are Valrhona's "blonde" chocolate, made with a slow-cooked white chocolate base, and Callebaut's ruby chocolate, made in a milk chocolate style with distinctly-processed cacao beans. But only the first three types of chocolate have stood the tests of time and public scrutiny.
Dark chocolate can be as simple as cacao beans refined into a smooth paste, called 100% dark chocolate. But cacao can have a bitter flavor, so chocolate makers usually add sugar, sweetening the chocolate and smoothing out harsher flavors. Some makers also add extra cacao butter, to further refine and coax out more complex flavor notes. Cacao percentage in dark chocolate can as low as 50%, but it’s still often praised as being the healthiest chocolate due to the bioavailability of its antioxidants and minerals and nutrients.
Milk chocolate is a chocolate bar that legally must contain milk. Usually milk chocolate contains cacao, milk powder, sugar, and often extra cocoa butter. Unlike dark chocolate, additional cocoa fat is almost always needed to balance out the milk solids, as milk chocolate usually has the same amount of sugar as dark chocolate. As a result, cacao percentage in milk chocolate is usually lower than dark chocolate. Milk chocolate has been criticized because milk’s proteins bind to the antioxidants in chocolate, rendering them less bioavailable. Some chocolate makers combat this by using non-dairy milk powders in their chocolates, though these products cannot legally be called milk chocolate.
To combat the norm that all milk chocolate is sweet and must contain dairy, craft chocolate makers (LINK) have introduced “dark milk” chocolate. It’s often 45% cacao or higher, and made with too low a percentage of milk solids to legally call it milk chocolate. Sometimes it contains zero milk solids, rather made with alternative creamers such as coconut milk or oat milk. Legally these are dark chocolates with milk as an inclusion, but even a small amount of added milk can completely transform a chocolate’s flavor.
White chocolate is cocoa butter plus milk powder and sugar. It’s different from milk chocolate in that it contains no cocoa solids, and up until 2002, it wasn't legally considered chocolate in the United States. White chocolate doesn’t contain any cacao solids, which are the part of the plant containing all the nutrients and antioxidants, so it often receives the complaint that it’s not “real chocolate.” But part of that issue is historical; since there was no legal definition of white chocolate for decades, a variety of products (some with no cocoa ingredients whatsoever) were marketed under that moniker.
Real cocoa butter contains a chocolaty aroma and a large proportion of healthy fats. Since it melts at body temperature, it’s valuable within the cosmetics industry. Low-quality cacao butter concentrated in the food industry, the chocolaty aroma removed to further distance it from milk and dark chocolates. It became easier to dilute with cheaper fats and excess sugar, making it seem less like chocolate and more like milky candy. Once white chocolate was legally defined by the FDA, the landscape of flavors offered in white chocolate began to shift towards more of the creamy, chocolaty bars on the market today
While the hype around Valrhona's blonde chocolate died down years ago, Callebaut's ruby chocolate is still very new to the market, released in 2017. Ruby chocolate is different from other milk chocolates because it’s made with cacao processed proprietarily, removing any traditional chocolaty flavor. Somewhere in that processing, the bright purple tones of the unprocessed “ruby cacao” seeds are preserved using acid, lending the chocolate its signature pink. Ruby chocolate’s been highly criticized since its debut, and up until recently, it couldn't legally be called chocolate in the United States.