Skin diseases encompass a wide range of conditions that affect the skin, hair, and nails. Common symptoms include redness, itching, swelling, and changes in skin texture or color. Causes can vary from infections, allergies, genetic factors, to environmental influences. Diagnosis typically involves a physical examination, medical history review, and sometimes skin biopsies or blood tests. Treatment options depend on the specific condition and may include topical creams, oral medications, lifestyle changes, and in some cases, surgical procedures. It's important to consult a healthcare professional for an accurate diagnosis and appropriate treatment plan.