The esophagus is the tube that carries food and liquids from your mouth to the stomach. Gastroesophageal reflux disease (GERD) happens when a band of muscle at the end of your esophagus does not close properly allowing stomach contents to leak back into the esophagus and irritate it – causing inflammation and erosions (i.e., breaks in the mucosal lining of the esophagus).
Click here for more information http://www.nlm.nih.gov/medlineplus/esophagusdisorders.html