Gastroesophageal Reflux Disease (GERD; or GORD when spelling oesophageal, the BE form) is the retrograde flow of gastric juice (gastric acid) and/or duodenal contents (bile acids; pancreatic juice) into the distal esophagus, commonly due to incompetence of the lower esophageal sphincter (LES).
The most prominent symptom of GERD is heartburn, the sensation of burning pain in the chest coming upward towards the mouth caused by reflux of acidic contents from the stomach to the esophagus.
The upper part of the stomach is wrapped around the LES to strengthen the sphincter and prevent acid reflux and to repair a hiatal hernia.