Gastroesophageal reflux disease (GERD) is defined as the failure of the antireflux barrier, allowing abnormal reflux of gastric contents into the esophagus. It is a condition which develops when the reflux of stomach contents causes troublesome symptoms and complications. It is a mechanical disorder which is caused by a defective lower esophageal sphincter (LES), a gastric-emptying disorder, or failed esophageal peristalsis.