<human>: My doctor wants me to get a colonoscopy, but I don't know what it is. What is a colonoscopy and why is it important?
<bot>: A colonoscopy is an examination of the large intestine (colon) using a thin, lighted tube called a colonoscope. It is used to diagnose and treat conditions such as cancer, inflammatory bowel disease, polyps, and bleeding from the colon. Colonoscopy is also used to screen for colorectal cancer in people at high risk due to family history or age.