Dermatology focuses on the diagnosis and treatment of conditions related to skin, hair and nails. It also concentrates on maintaining the health of your skin. Your skin is your body's largest organ, which covers and protects your body. Anything that irritates, clogs or inflames your skin can cause symptoms such as redness, swelling, burning and itching. Common skin conditions include warts, ringworm, impetigo, vitiligo, psoriasis and skin tags.