Lanolin, also known as wool wax, is a natural ingredient of animal origin obtained from sheep’s wool. It is a waxy substance secreted by sheep to protect their fleece, extracted during the washing of raw wool, then purified and refined for cosmetic use. From a chemical standpoint, lanolin is a complex mixture of lipids, mainly composed of esters of fatty acids and alcohols, which makes it very similar to human sebum. This affinity gives it excellent compatibility with both skin and hair. In cosmetic formulations, lanolin is known for its emollient, occlusive, and relipidizing properties. It forms a protective film on the skin’s surface, reducing water loss and helping to restore the skin barrier. It is particularly suited for dry, sensitive, damaged, or chapped skin, helping to soothe, soften, and protect it. Its high water absorption capacity also allows it to act as an indirect moisturizing agent and to stabilize formulations. It also functions as an emulsifier, facilitating the blending of water and oil phases, and contributes to improving the texture, stability, and overall performance of cosmetic products. Thanks to its properties, lanolin is widely used in rich creams, repairing balms, lip care products, ointments, hair care, and hand and nail treatments, where it provides nourishment, protection, and comfort.