A dermatologist is a physician who specializes in the medical and surgical treatment of skin conditions and diseases. Dermatologists are certified by the American Board of Dermatology after extensive education and medical residency. Dermatologists are highly trained diagnosticians and can distinguish between conditions that share similar symptoms. They treat minor skin conditions such as rashes, chronic skin diseases such as psoriasis, and the different types of skin cancer. Today many dermatologists are also well versed in cosmetic dermatology procedures to help improve the appearance of skin as we age.