This document provides information on gastrointestinal bleeding, including its anatomy, definition, epidemiology, clinical features, etiology, history and examination, investigation, and management. It discusses the major sites of upper and lower GI bleeding. For upper GI bleed, common causes include peptic ulcers, esophageal varices, erosive gastritis, and cancers of the esophagus and stomach. Clinical features, risk factors, pathophysiology, and treatment approaches are described for several specific conditions that can cause GI bleeding.