Lecithin

Lecithin is a natural chemical present in every cell membrane, making it indispensable for sustaining cell membrane functions. Because of its role, lecithin finds many uses in cosmetics, from an emulsifying agent to a nutritional additive; hence, it has become one of the important cosmetic formulation ingredients.
Lecithin is an emollient that smoothens the skin by simply locking in moisture and improving the skin's natural barrier. As a water-binding agent, lecithin attracts and holds water within the skin, promoting hydration that aids in sustaining healthy, supple skin.
Besides moisturizing properties, lecithin is also an effective emulsifier that has the ability to combine cosmetic products with a combination of oils and water-based ingredients; its emulsifying property acts as a stabilizer, making the formulation even and retaining the effectiveness of the ingredients.
Probably the most precious of lecithin's functions in skincare is the ability to form liposomes. Basically, liposomes are small vesicles consisting of a lipid bilayer that can deliver active ingredients deeper into the skin, increasing their action.
Overall, lecithin is considered to be a multi-functional ingredient, with moisturization-emulsification-stability effects; it improves the delivery of active ingredients for better skin health.