Meringues are made by beating egg whites into a foam and adding sugar. There are different types of meringues depending on the amount of sugar used and how it is incorporated. Cold meringues use less sugar added after foaming. Hot and boiled meringues add more sugar, with hot meringues adding warmed sugar and boiled/Italian meringues cooking the sugar into a syrup before adding. Proper technique and ingredient quality are important for achieving stable meringue foam.