A colonoscopy is a medical procedure used to examine the inner lining of the large intestine, or colon. During the procedure, a long, flexible tube with a camera, called a colonoscope, is inserted through the rectum. This allows doctors to look for abnormalities, such as polyps or signs of cancer, and to take biopsies if necessary. Colonoscopy is often recommended for individuals over the age of 45 or those with a family history of colorectal cancer. The procedure typically requires preparation, including a special diet and cleansing of the bowel. It is usually performed under sedation to ensure patient comfort.