Your skin is an organ composed of a layer of tissues that protect underlying muscles and organs. Skin is used for insulation, vitamin D production, sensation, and excretion (through sweat).
Mammalian skin often contains hairs, which in sufficient density is called fur. The hair mainly serves to augment the insulation the skin provides. On some animals the skin is very hard and thick, and can be processed to create leather.
Damaged skin will try to heal by forming scar tissue, often giving rise to discoloration and depigmentation of the skin.
The skin is often known as "the largest organ in the human body": this applies to exterior surface, as it covers the body, appearing to have the largest surface area of all the organs. Moreover, it applies to weight, as it weighs more than any single internal organ. For the average adult homo sapiens, it has a surface area of between 1.5-2.0 square metres.
The skin on a person's face is seen by people that person interacts with. For some people, then, facial skin care is of importance, and cosmetics are made to deal with the appearance of the person's face and condition of the skin, such as pore control and blackhead cleansing.
