Lesions are areas of tissue that have been damaged or altered due to injury, disease, or infection. They can appear on the skin, organs, or other parts of the body and may vary in size, shape, and color. Common types of lesions include ulcers, tumors, and rashes. Lesions can be benign, meaning they are not harmful, or malignant, indicating they may be cancerous. Diagnosis often involves physical examination and may require imaging tests or biopsies. Treatment depends on the underlying cause and can include medication, surgery, or other therapies.