Very simply, a meringue is a mixture of stiffly beaten egg whites and granulated sugar. In order for the sugar to dissolve completely (and therefore produce an absolutely smooth meringue), it must be beaten into the whites a tablespoon at a time. Soft meringue is used as a swirled topping for pies, puddings and other desserts such as baked alaska. It's baked only until the peaks are nicely browned and the valleys golden. Hard meringues begin by being piped onto a parchment-lined baking sheet. They're usually round and may be large or small. They're then baked at a very low temperature (about 200°F) for as long as two hours and left in the turned-off oven until completely dry. Hard meringues often have a center depression that is filled with ice cream, custard, whipped cream and fruit, etc. Tiny, one- or two-bite size, mound-shape meringues are called kisses and are eaten as a confection. Kisses often contain chopped nuts, cherries or coconut. They may be baked until completely dry or just until crisp on the outside and chewy inside. An Italian meringue is made by gradually pouring hot sugar syrup over stiffly beaten egg whites, then beating constantly until the mixture is smooth and satiny. This versatile mixture may be used to create either soft or hard meringues.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.