Folding is a technique used to gently combine a light, airy mixture (most often beaten egg whites) with a heavier mixture. The lighter mixture is placed on top of the heavier one in a large bowl. Using a rubber spatula, you fold by cutting down vertically through the two mixtures, across the bottom of the bowl and up the nearest side. With each fold, the bowl is rotated a quarter turn. This gentle motion turns the mixtures over on top of each other, combining them in the process.