What does it mean to "fold" ingredients in cooking?

Folding is a crucial technique in cooking that involves gently combining light and heavy mixtures to maintain the airy structure of the lighter ingredients, such as whipped cream or beaten egg whites. This process is achieved by sliding a spatula or a spoon down the side of the bowl, underneath the mixture, and then lifting it over the top in a gentle motion. The goal is to thoroughly incorporate the heavier ingredient, like batter or fruit, without deflating the lighter one.

This technique is particularly important in recipes like soufflés or mousses, where maintaining volume is key to achieving the desired texture. When done correctly, folding helps create a harmonious blend, allowing the dish to retain its intended lightness and fluffiness, which may otherwise be lost with vigorous mixing methods.