A dermatologist is a physician who, after completing medical school, trains four more years to become a specialist in the treatment of skin disease. Upon finishing that residency program, a dermatologist is eligible to take the qualifying examinations to become a Diplomate of the American Board of Dermatology. Once Board certified, a dermatologist can then become a Fellow of the American Academy of Dermatology. With this rigorous preparation, dermatologists are expert in the treatment of disorders of the skin, hair, and nails, as well as the prevention of disease, and the enhancement of the appearance of the skin.