The skin is the outer covering of the body. In humans, it is the biggest organ of the integumentary system. The skin has multiple layers of ectodermic tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals, except that it is not protected by a pelt. Though almost all human skin is covered w/ hair follicles, it appears hairless. There are two common types of skin, hairy and glabrous skin. The adjective cutaneous literally means "of the skin" (from Latin cutis, skin).

Because it interfaces w/ the environment, skin plays a key role in protecting (the body) against pathogens and excessive water loss. Its another functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates. Seriously damaged skin will try to heal by forming scar tissue. This is often discolored and depigmented.

In humans, skin pigmentation varies among populations, and skin type can range from dry to oily.