Skin is one of the largest organs in the body, accounting for 16% of body weight. Its surface area is about 1.5-2 square meters. Its thickness varies according to age, sex, nutritional status and location. It is usually 0.5-5 millimeter, the skin thickness is 0.2-3 mm, the eyelids and axillary skin are thinner, the palmar and foot skin are the thickest, and each inch skin is the most. Skin contains millions of cells and intricate blood vessels and neural networks, and skin appendages, such as hair follicles, sebaceous glands, and sweat glands, contain every square inch of skin: 65 hair, 9500000 cells, 95-100 skin glands, 78 heat perception organs, 13 cold sensory organs, 70 meters nerve, 7 meters of blood vessels, 60-165 bars. Pressure tactile, 650 sweat glands, 1,300 nerve endings showing pain, 19,500 nerve tissue endings and perception cells.