Folding is a gentle way of mixing ingredients. This technique is usually used when blending a light airy ingredient (such as whipped egg whites or whipped cream) into a heavier one. Folding helps to maintain some of the airy texture. You will almost always be adding the lighter ingredient into the heavier one, not the other way around. Use a rubber spatula to fold ingredients into each other. Before beginning to fold, stir about a quarter of the light mixture into the heavy one (this will "lighten" the entire batter and help with folding). Next, pour the light mixture on top of the batter. Using your rubber spatula, cut through the mixtures to the bottom of the bowl and "fold" the batter on the bottom over the light ingredients at the top. Repeat this mixture until the two are blended, but not until you've lost the fluffy texture of the light ingredient. The basic motion is bottom ingredients are lifted then folded gently over the top. Lift and fold.