This document provides an overview of gastrointestinal (GI) bleeding, including its causes, symptoms, diagnosis, and treatment. GI bleeding is classified as upper or lower depending on its location in the GI tract. Common causes of upper GI bleeding include peptic ulcers, gastritis, esophageal varices, and cancers. Lower GI bleeding is often caused by diverticulosis, cancers, inflammatory bowel disease, infections, angiodysplasia, polyps, and hemorrhoids. Symptoms include vomiting blood, black stools, and fatigue. Diagnosis involves medical history, physical exam, endoscopy or colonoscopy, and lab tests. Treatment depends on severity but may include IV fluids, blood transfusions, surgery, or