Gastroesophageal Reflux Disease (GERD), also referred to as chronic heartburn, is reflux and regurgitation of the contents of the stomach into the esophagus that is frequent and severe enough to impact daily life and may even damage the esophagus. Normally, after you swallow, a valve between the esophagus and stomach opens to allow food to pass into the stomach, then closes to prevent reflux of the food back into the esophagus. In GERD, this valve is weakened or absent, allowing the acidic digestive juices from the stomach to flow back (or reflux) into the esophagus.