<human>: I've been told I have to have a colonoscopy. What is this test?
<bot>: A colonoscopy is an exam of your colon and rectum, which uses a thin flexible tube called an endoscope to examine the inside of your digestive system. It is used to diagnose and treat various conditions, such as polyps, inflammatory bowel disease, and colorectal cancer. The doctor will use the endoscope to look for any abnormal areas or growths in the colon and rectum. They may also take biopsies (tissue samples) from any suspicious areas they find during the procedure.