Beat Soft, Firm, and Stiff Peaks in Egg Whites
Pillow-like quality of whipped egg whites is terribly useful when baking things. Good whipped egg whites make souffles and cakes rise, lighten pancakes and waffles, and can be sweetened and turned into meringue, among their many uses.
Start With Fresh Eggs and Separate Them
Be very careful when you separate the eggs. Any yolk that makes its way into the whites will keep the whites from whipping up as big and fluffy as possible.
Beat the Egg Whites: Soft Peaks
When you turn your whisk upside down the peaks are just starting to hold. They're soft and melt back into themselves after a second.
If you keep beating the egg whites, they will quite quickly go from soft peaks to firm peaks. The difference is that firm peaks keep their shape without drooping.
Turn the whisk upside down, and those peaks hold proudly stable! You should see they point straight up without collapsing at all. Now the mixture is thick and heavy.