Peptic ulcer disease is caused by an imbalance between aggressive factors like acid and pepsin and defensive mucosal factors. Helicobacter pylori infection is the most important cause, causing chronic gastritis. Smoking, NSAIDs, and genetic factors also increase risk. H. pylori eradication is the cornerstone of treatment and prevents recurrence in most cases. Symptoms include recurrent abdominal pain relieved by food or antacids. Endoscopy is required for diagnosis and management involves eradication of H. pylori along with acid suppression medications.