A colonoscopy is a medical procedure used to examine the inner lining of the large intestine, which includes the colon and rectum. 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. Before a colonoscopy, patients typically follow a special diet and take laxatives to clear the intestines. The procedure usually lasts about 30 minutes and may involve sedation for comfort. Afterward, patients can resume normal activities, but they may need someone to drive them home due to the sedation.