This document discusses gastrointestinal bleeding (GIB). It is classified as upper GIB, arising above the ligament of Treitz, or lower GIB, arising below. Common causes of upper GIB include peptic ulcer disease, portal hypertension, Mallory-Weiss tears, and vascular anomalies. Initial management involves fluid resuscitation and endoscopy for diagnosis and treatment. Lower GIB causes include diverticulosis, angiodyplasia, and inflammatory bowel disease. The document provides details on evaluation, diagnosis, and management of GIB.