Dermatology (dermatology) is the branch of medicine that deals with the skin and diseases of these structures, such as the skin, nails and hair. This branch of medicine includes the diagnosis, treatment and prevention of skin diseases. Skin diseases can occur for many reasons. The most common skin conditions include acne, eczema, dermatitis, fungal infections, warts, lichen planus, rosacea, acne vulgaris, psoriasis, vitiligo, melasma, and moles. Most of these diseases are manifested by skin rash, itching, lesions, rashes or other skin changes. Dermatologists examine patients and review their medical histories to diagnose skin conditions. Blood tests, biopsies, or other tests may be done to confirm the diagnosis. Treatment methods may vary depending on the type and severity of the disease. Topical or systemic medications, laser treatments, phototherapy, surgery, or other procedures may be used. Dermatology also provides information on preventive measures for skin health, including skin cancer screening and treatment. When skin cancer is detected early, the chances of success are higher, which is why dermatologists recommend screening for skin cancer once a year.