Place egg whites in a clean, dry, grease-free bowl and use equally clean beaters.
Beat on a slow speed to build up a foam, and then increase the speed.
Soft peaks are when the whites are voluminous but they barely hold their shape when the beaters are lifted (for lightening batters).
Medium peaks just begin to hold their shape, but droop when the beater are lifted (for souffles).
Stiff peak egg whites completely hold their shape. Whisk in sugar at this stage to make meringues.