The skin is the largest and fastest-growing organ of the human body. It plays an important immunity role and has very specific functions in maintaining body temperature and protecting the body against pathogens. Dermatology is the branch of medicine dealing with the skin, nails, hair and its diseases. It is a speciality with both medical and surgical aspects. Dermatologists specialize in diagnosing and treating conditions related to the skin, hair and nails, including concerns related to cosmetic issues and other medical skin conditions.