Shea butter has a long history in African culture, and is used by many tribes not only for their skin and hair, but in cooking, to make medicinal ointments, to make soap and even as a sunblock. It is refined from the nuts of the shea tree, and chemically shea butter is a triglyceride, which is a major component of the oils in your skin.
For skin and hair care shea butter is deeply nourishing and moisturizing. It is a humectant, which means it pulls in water from the air, and when applied to the skin it binds that water so it doesn't easily evaporate. It also has anti-inflammatory properties and does offer some protection against the sun's ultra violet rays.