There are many types of brandy, but the most elegant is Cognac. Cognac is to brandy what Champagne is to sparkling wine: A single type of brandy with strict production rules.
Cognac is distilled twice; the first distillation creates brouillis, and the second creates eau-de-vie, which must be aged in French oak barrels for at least two years.
Under the AOC, Cognac must have an alcohol by volume of at least 40%. In the United States, brandy must have an ABV of at least 40%, but some have an ABV as high as 60%.
Cognac is drier than most brandies because it is made with a dry white wine and can have no more than 1.5 grams of sugar per liter. It can be drunk neat or mixed into cocktails.
Most brandies can be consumed on their own or on the rocks. In cocktails, brandy is rarely mixed with sodas; instead, it's usually blended with creamy ingredients like egg whites.