The skin is a vital organ that covers the entire outside of the body, forming a protective barrier against pathogens and injuries from the environment. The skin is the body’s largest organ; covering the entire outside of the body, it is about 2 mm thick and weighs approximately six pounds. It shields the body against heat, light, injury, and infection. The skin also helps regulate body temperature, gathers sensory information from the environment, stores water, fat, and vitamin D, and plays a role in the immune system protecting us from disease.

The color, thickness and texture of skin vary over the body. There are two general types of skin; thin and hairy, which is more prevalent on the body, and thick and hairless, which is found on parts of the body that are used heavily and endure a large amount of friction, like the palms of the hands or the soles of the feet.