What component contributes to the fluffiness of omelets when properly cooked?

The component that contributes to the fluffiness of omelets when properly cooked is the incorporation of air. When eggs are beaten, air cells are formed within the mixture. This process is crucial because, during cooking, the trapped air expands, helping to give the omelet its light and airy texture. The gentle heat causes the proteins in the eggs to coagulate and set while the air bubbles expand, resulting in a fluffy omelet.

While other components like egg yolk, milk, and butter can influence the overall flavor and richness of the omelet, they do not directly contribute to the fluffiness in the same way that air incorporation does. Milk may add creaminess, and butter can add flavor and moisture, but without the proper aeration, the omelet would not achieve the desired lightness.