The fluffy, almost pillow-like quality of whipped egg whites is a terribly useful thing. Whipped egg whites make souffles and cakes rise, lighten pancakes and waffles, and can be sweetened and turned into meringue, among their many uses.
Many home cooks are daunted by the prospect of whipping egg whites, but really, nothing could be easier. This guide shows you how to whip them, and shows you the stages (soft peak, firm peak, stiff peak) so you'll feel confident when you take it on yourself.
When you whip egg whites, you're essentially forcing air into the egg whites, causing the protein in the egg whites to stretch and create bubbles around the water within the whites. First the egg whites will reach soft peaks (you can remove the whisk or beaters and a peak will form, and then droop), then firm peaks (when you remove the whisk or beaters the peak that forms will keep its shape), and then stiff peaks (not only does the peak on the egg white surface hold, but so will the peak on the whisk or beaters when turned to peak upwards as shown above).
Watch these stages carefully, because if you over-beat the egg whites the stretched protein will break and let the water in the whites out, creating a really unappetizing mix of eggy water and foam.