Endoscopy is a foundational centerpiece to the clinical practice and science of gastroenterology. Endoscopic examination allows multilayered perspectives on digestive health and disease, from the level of organ-based physiology to the level of the mucosa and, increasingly, to the level of cellular structures. Endoscopic diagnostic and therapeutic capabilities have grown in tandem. Advances in endoscopic imaging technologies have substantially augmented the diagnostic acumen of the gastrointestinal endoscopist.