Hemorrhoids are swollen and inflamed veins in the rectum and anus that can cause discomfort, bleeding, and itching. They can be classified as either internal, occurring inside the rectum, or external, appearing under the skin around the anus. Factors contributing to hemorrhoids include straining during bowel movements, prolonged sitting, and pregnancy. Treatment options range from lifestyle changes and over-the-counter remedies to medical procedures in more severe cases.