Hemorrhoids, also known as piles, are swollen veins in the rectum and anus. They can be internal, located above the dentate line, or external, located below the dentate line. Common causes include straining during bowel movements, obesity, pregnancy, and aging. Symptoms may include painless bleeding, prolapse, itching and discomfort. Diagnosis is usually based on medical history and physical exam. Treatment options range from lifestyle and diet changes to over-the-counter creams and suppositories for mild cases, and procedures like banding or surgery for more severe cases.