Lately many food specialty stores have been carrying a wide assortment of chocolate bars from different countries. Some of my friends are comparing and discussing the merits of these chocolates as if they were wines. Mostly, they talk about "percent," but percent of what? Also, I find the ingredient lists on the wrappers confusing. Can you help me sort these things out so I can be as snobbish as my friends?

It has been almost three years since I wrote about chocolate in this column, which is surprising because I rarely go for three days without eating some. Yes, I'm a chocophile (a more rational description than chocoholic).

Only a few years ago Americans discovered chocolate is not limited to Hershey bars and Whitman Samplers -- that serious chocolate bars, as distinguished from candy bars, could open a whole new world of flavors. There are dozens of chocolate bars now on the market from the United States and abroad. Chocolate tastings are threatening to replace wine tastings and olive oil tastings as entertaining and educational activities.

Let's look closely at what's in a bar of good, dark chocolate. The ingredient lists on the wrappers can indeed be perplexing, because most of the ingredients go by a number of aliases.

It all starts with cacao (kah-KAY-oh), not cocoa, beans. Cacao beans are the seeds of the fruit of the tropical tree Theobroma cacao. (Theobroma literally means "food of the gods," a name obviously chosen by a chocophile botanist.) The bitter cacao bean was enjoyed as a spice by the Mayans and Aztecs, but only after it made its way to Europe was it sweetened with sugar.

The percentage number on a bar's wrapper represents the bar's weight that actually comes from the cacao bean; that is, it's the bar's content of honest-to-goodness cacao bean components. Natural cacao beans contain 54 percent fat by weight; the other 46 percent, as with most seeds, is solid vegetable matter. Thus, the percentage number on the wrapper of a chocolate bar is the sum of its cacao fat (called cocoa butter in the United States) and its cacao solids.

The rest of a chocolate bar is almost entirely sugar, so a "77 percent" chocolate bar will contain about 23 percent sugar. The higher the percentage number on the wrapper, then, the lower the percentage of sugar and the less sweet, more bitter and complex the flavor of the bar will be. Minor ingredients, usually present in quantities at less than 1 percent, may include vanilla or vanillin (an artificial flavor) and lecithin, an emulsifier obtained from soybeans that enhances the chocolate's smoothness and creaminess.

Here are three major components of a quality chocolate bar:

* Chocolate liquor, cacao, also known as cacao mass, cacao paste or cacao liquor: By any of these names, this is the "raw material" -- ground-up, whole cacao beans. Chocolate personified. It is often referred to as a paste or liquor because the friction of grinding melts the dense fat, and what comes out of the grinding machine is a glistening, brown paste.

Unsweetened chocolate, or baking chocolate, is simply chocolate liquor that has been poured into molds and solidified by cooling. The FDA requires that it contain between 50 percent and 58 percent fat, a leeway of 4 percent on either side of natural cacao beans' fat content of 54 percent.

* Cacao butter, or cocoa butter: the fat from the cacao bean. "Butter" is a more appealing word than "fat," but don't let it fool you into thinking it comes from a cow. Not even a brown cow.

* Cocoa, or cocoa solids/cacao solids: The brown, solid parts of the cacao beans, ground to a powder.

That's it. Just three main players -- whole chocolate, its fatty part and its solid part. The problem is identifying them by their stage names in the lists of ingredients.

Chocolate factories often squeeze the fat out of whole cacao, thus separating the fat from the solids. The fat-free solids are commonly and quite properly called "cocoa" and are sold as such. Manufacturers often add some of the separated fat to their formulas for chocolate bars to adjust the smoothness and melting properties. Because this added cocoa butter changes the cacao's natural 54-to-46 ratio, it is listed separately as an additive in the list of ingredients. The percentage number on the wrapper includes this added fat.

Note that I have not included milk, milk solids or nonfat milk among the ingredients because I don't consider milk chocolate to be chocolate. It's just candy. Milk chocolate contains so much milk and sugar that its percentage of true cacao may be as low as 10 percent, the minimum required by the FDA for calling it "chocolate" on the label. Hershey's milk chocolate contains about 11 percent cacao. In contrast, a serious dark chocolate bar will contain anywhere from 65 percent to 85 percent cacao.

In the European Union, as a result of squabbling among Belgium, the United Kingdom, France, Germany and other countries, the minimum amount of cacao has been set at only 1 percent! That's why many of the best European dark chocolate bars tout their high cacao content by printing their percentage numbers in huge type on their wrappers.

If you're truly interested in upping your snob quotient, taste and test as many serious dark chocolate bars as you can find (or afford; they're not cheap). Use the percentage of cacao only as an initial indicator of how sweet or bitter you like your chocolate. Then try a variety of bars in that range to find your favorites as far as texture (brittleness, or "snap"), flavor and mouth feel are concerned. Learn the cacao percentages and countries of origin of a few favorite chocolate bars, and at every opportunity, talk about their flavors in terms taken from a wine magazine (bouquet, fruit, finish, etc.). Use the word cacao (not cocoa) as often as possible, and you can be as good a chocolate snob as any of your friends.

LABELINGO: Perspicacious reader Joy Reynolds of Washington sends the wrapper from a package of Snak Club Yogurt Nut Mix, the first named ingredient of which is, of course, raisins. The label claims that it is a "Product of the U.S.A." but "May contain ingredients from Mexico and/or China and/or India and/or Brazil and/or Africa."

(Have you noticed any silly things on food labels? Send your Labelingo contributions, along with your name and town, to Food 101, Food Section, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or to the e-mail address below.)

Robert L. Wolke (www.professorscience.com) is professor emeritus of chemistry at the University of Pittsburgh and the author, most recently, of "What Einstein Told His Cook: Kitchen Science Explained" (W.W. Norton, hardcover, $25.95). He can be reached at wolke@pitt.edu.