Hair, sebaceous glands, exocrine sweat glands, parietal sweat glands and nails are all appendages of the skin. A. Hair is a long cylindrical keratinous structure, the part of which is deep inside the skin is called hair root, and the end of the hair root is expanded in the shape of onion head, called hair bulb. The part of the skin that is exposed is called the hair stem. Hair distribution is very wide, almost all over the body, only in the palmoplantar, finger (toe) surface, finger (toe) end extension surface, lip red area, glans, foreskin inner surface, labia minora, labia majora inner and pubic emperor and other places hairless. Usually hairs can be divided into:1. Stiff hairs: Stiff hairs are thicker, with medulla and darker in color. (1) long hair, such as hair, beard, axillary hair and pubic hair, etc.; (2) short hair, such as eyebrows, eyelashes, nose and ear hair, etc., usually shorter than the length of the long hair for short. 2, Cui hair: Cui hair is fine and soft, no medulla, lighter color, mainly seen in the face, limbs and trunk. Second, the distribution of sebaceous glands is very wide, in addition to palmoplantar and finger (toe) surface, almost throughout the body. Usually can be divided into three types: 1, attached to the hair follicle, such sebaceous glands open in the hair follicle, and hair together constitute the hair sebaceous gland unit; 2, related to the fine hair, its ducts directly open in the body surface; 3, and hair has nothing to do with, so also known as independent sebaceous glands, seen in the mouth lips, the inner surface of the foreskin, the labia minora, the inner side of the labia majora, the pubic emperor and such as cloud. The distribution density of sebaceous glands in the human body varies, with the scalp and face (especially the forehead, nose, etc.) being the most numerous, while the trunk has more central parts, so these parts and the armpits are also called sebaceous overflow areas. The extremities (especially the outer calves) have the least sebaceous glands, while the palmoplantar and finger (toe) surfaces are absent. Therefore, the palm of the hand skin often need to moisturize the hand cream. The sweat glands are divided into exocrine sweat glands and parietal sweat glands according to the structure and function of the sweat glands. The exocrine sweat glands, also known as small sweat glands, can be referred to as sweat glands, at the lips, red lip area, glans, inner surface of the foreskin, outside the clitoris, almost all over the body. The density of sweat glands varies in different parts of the body, with the palmoplantar glands having the highest density, followed by the frontal glands. Generally, the flexors of the limbs are more dense than the extensors, and the upper limbs are more dense than the lower limbs. The density of sweat glands in children’s skin is greater than that of adults. The sweat gland is a relatively simple structure of the blind end of the tubular gland, its glandular part of the self-circulating irregular spherical, mostly located in the dermis and subcutaneous tissue junction, its duct from the gland vertical or slightly curved upward, through the dermis greatly epidermal end of the lower end into the epidermis opening on the skin surface.