Skin covers all our body except for the eyes. It provides a barrier against organisms and protects us from minor injuries. It is water-proof. The skin helps to maintain our body temperature.
When we feel hot, the skin changes color because tiny capillary blood vessels in the skin expand and heat is lost from the blood.It also helps to retain body heat during cold conditions by narrowing the blood vessels in the skin.
The skin being waterproof prevents moisture from escaping. Although we sweat during summers, this is useful as it cools down the body. The skin contains many nerve endings and receptors, which give us sense of cold, heat, touch and pain.