How does cocoa butter actually help dry, rough skin?

Cocoa butter is a plant fat rich in three main fatty acids: stearic acid, palmitic acid, and oleic acid. Stearic and palmitic acids are saturated fats that help create a soft, protective film on the skin's surface, slowing evaporation of moisture from the stratum corneum. Oleic acid, a monounsaturated fat, contributes to a supple, nourished feel. Together, these lipids mimic some of the skin's own barrier lipids, reinforcing the surface barrier temporarily. A practical advantage of cocoa butter is its melting range — it starts to soften around 34–38 °C, so it turns from a semi-solid cream into a smooth oil on contact with warm skin. This means you get the spreadability of an oil with the stay-put coverage of a thicker cream, and it doesn't leave the tacky or waxy finish that some high-melting-point butters can. The effect is cosmetic: skin feels smoother, less tight, and less coarse while the product is on it.