Where it was made. In Europe, the word Champagne (capital C) refers to a specific region in France. The government regulates the kinds of grapes and method of preparation.
In the United States, champagne (small c) has become a generic term for a variety of sparkling wines. Law requires that the state of origin and the process be shown on the label. Italy offers Asti Spumante, Spain and France have blanc de blancs, and Germany produces sekt.
How it was made. France's traditional way, methode champenoise, considered the best by purists, doesn't appear on French Champagne labels because it is the only method. This method of identification does appear on some of the best American and Spanish sparkling wines.
Another style is the Charmat bulk process, which will appear on labels. This champagne can be quite flavorful and effervescent.
Carbonated wines are produced by adding fizz using carbon dioxide under pressure.
What color it is. Most sparkling wines are white, especially the best ones. Some champagnes are almost clear except for the bubbles. They're often labeled blanc de blancs -- white wine made from white grapes only. Light-colored champagne can be made from dark-skinned grapes for a rich, deep-gold hue.
The best French Champagnes are made from chardonnay (white) and Pinot Noir (red) grapes. White Riesling grapes are used to make sekt wines in Germany. For the kinds of grapes used to make sparkling wines in the U.S. and other countries, read the label.
Pink and rose champagnes are made with dark grapes and are considered quite good. Sparkling burgundy, definitely red, lacks distinction.
How dry or sweet it is. Public taste has moved toward light, dry (not sweet), sparkling wines. The driest easily available white champagnes are labeled brut. Extra dry is sweeter! Dry or sec wines are even sweeter but not sugary. Pink champagne's flavors will be on the sweet side but not so labeled. German sekt tends to be rather sweet; Italy's Asti Spumante is the sweetest.
What its age is. White wines, including champagnes, are meant to be drunk while they are young. Not only do they not improve with age, they eventually begin to deteriorate. Excellent brands of champagne carry no date on their labels.
An integral part of the champagne experience is the presentation. Here are some tips: