Skin is the tough, flexible covering that protects the outside of your body. It's your largest organ, stretching over every part of you from head to toe, keeping your insides safe while letting you feel the world around you.

Your skin does remarkable work. It shields you from germs, helps control your body temperature through sweating, and heals itself when cut or scraped. Tiny sensors in your skin let you feel heat, cold, pressure, and pain: that's how you know to pull your hand away from a hot stove or feel the soft fur of a cat. Skin even makes vitamin D when sunlight hits it.

As a verb, skin means to remove the skin from something, like skinning a potato or skinning your knee in a fall.

The word appears in many expressions. To do something by the skin of your teeth means to barely succeed, escaping failure by the smallest margin. When something gets under your skin, it bothers or irritates you persistently. Having thick skin means not getting upset easily by criticism, while someone with thin skin gets their feelings hurt readily.

Animals have skin too, though we sometimes use different words for it: a snake sheds its skin, leather comes from cow skin (called hide), and we peel the skin off an apple or potato before eating it.