Lanolin is a waxy substance that sheep naturally produce to protect their wool. Because lanolin's properties are similar to those of the sebum (oil) secreted by human skin, it is a popular ingredient in moisturizers, hair care products, and soaps. It is also widely promoted as a natural remedy for sore nipples due to breastfeeding.
Hydrolysis of lanolin yields lanolin alcohols and lanolin acids. Lanolin alcohols are a rich source of cholesterol (an important skin lipid) and are powerful water-in-oil emulsifiers; they have been used extensively in skincare products for over 100 years. The grease/oil is extracted from the wool after it is shaved from the sheep.