GERD is one of the most common gastrointestinal disorders, affecting up to 15% of individuals. It results from backflow of stomach contents into the esophagus, which is normally prevented by the lower esophageal sphincter and other anatomical protections. Symptoms include heartburn and acid regurgitation. Risk factors include hiatal hernia, excess stomach acid production, delayed gastric emptying, and decreased mucosal resistance. Complications include esophagitis, ulcers, Barrett's esophagus, and even esophageal cancer if left untreated. Treatment involves lifestyle changes, antacids, H2 blockers, proton pump inhibitors, and sometimes surgery for complications like strictures.