Peptic ulcers form in the stomach or duodenum due to an imbalance between acid secretions and mucosal defenses. Risk factors include H. pylori infection in 90% of cases, NSAID use, and stress. Complications include hemorrhage, perforation, and obstruction. H. pylori survives stomach acid through urease production. Diagnosis involves symptoms and imaging. Treatment depends on complications but usually involves antibiotics to eradicate H. pylori along with acid suppression. Surgery may be needed for perforation or obstruction.