Peptic Ulcer Disease is caused by breaks in the gastric or duodenal mucosa that are usually due to an imbalance between aggressive factors like acid and pepsin and protective ones like mucus and bicarbonate. H. pylori infection and NSAID use are major causes. Patients present with epigastric pain relieved by food or antacids. Diagnosis is usually made with endoscopy and tests for H. pylori. Treatment involves acid suppression, eradicating H. pylori with antibiotic combinations, and sometimes surgery for complications. Zollinger-Ellison Syndrome is a rare cause of ulcers due to a gastrin-secreting tumor.