The different varieties of chocolate are determined by the amount of cocoa each type contains. The higher percentage of cocoa makes the chocolate a higher quality and richer and deeper in chocolatey flavor.
If you are interested, you can read more about the history and origin of chocolate. It is fascinating to learn how chocolate is produced.
The word couverture means "to coat or cover." Couverture is used by professional bakers to make candy because it is a high quality product. Couverture has more cocoa butter than most other chocolate. It is this quality which aids in coating and dipping.
2. White Chocolate
Although some people disagree, real white chocolate can be truly called chocolate because it does contain cocoa butter, although it lacks any cocoa powder or "solids," which is why it is white. There are a number of imitation white chocolates that are produced using vegetable fat. These versions do not have any real chocolate flavor to them, but are often used in candy making.
3. Milk Chocolate
Milk chocolate is the "sweet" and most popular chocolate. It does, of course, contain cocoa solids, but also has added milk solids. This is what gives it that extra creamy texture. Milk chocolate usually contains about 20% cocoa solids.
4. German Chocolate
German chocolate is a form of dark chocolate, but it is a bit sweeter than semisweet chocolate. This chocolate gets its name from the man who developed it, Sam German, rather than the country of Germany.
5. Semisweet Chocolate
Semisweet chocolate is the most commonly used dark chocolate variety in baking. It has a nice amount of added sugar without being overly sweet. Dark chocolate can be substituted for most chocolates in recipes. It is very chocolatey because it has up to 75% cocoa solids in its make-up. Yummm.
6. Bittersweet Chocolate
Bittersweet chocolate is similar to semisweet, but contains even less or no sugar. Bittersweet is also made from up to 75% cocoa solids. It is considered a more sophisticated chocolate by some, especially fine chefs.
7. Bitter Chocolate
Bitter chocolate is also referred to as unsweetened chocolate or plain chocolate. Bitter chocolate contains absolutely no sugar and is very strong. You wouldn't want to eat it on its own, but it is great for use in baking and cooking.
These are just some of the basic chocolate varieties. Of course, we could also include gourmet, organic, belgian, swiss, and other terms when referring to varieties of chocolate. Realistically, though, all of these will basically fall in one of the types of chocolate categories above.