Endoscopy is the visual examination of the internal organs of the body with an instrument called an endoscope. 

An endoscope is a long, thin, flexible tube with a light and camera on the end. The endoscopist sees the camera images on a TV screen at the time of examination. 

Endoscopes are inserted through the mouth, anus or urethra. 

Endoscopy is not only a diagnostic test. The endoscope may take biopsies, aspirate secretions, remove a foreign body, give an injection (eg to stop bleeding), cauterize a spot, or insert a metal clip or metal drainage tube.