GERD stands for gastroesophageal reflux disease, which is the backflow of stomach contents (including stomach acid) upward into the esophagus (the swallowing tube that extends from the mouth to the stomach and sits behind the breast bone). The lining of the stomach protects the stomach from the effects of its own acids. Because the esophagus lacks a similar protective lining, stomach acid that flows backward (refluxes) into it causes heartburn (also called dyspepsia).
Many people experience heartburn occasionally; however, people who get heartburn or other GERD symptoms persistently are considered to have GERD. GERD is the most common acid-related condition in Canada. About 10% to 20% of the western world suffers from GERD. Adults, children, and even infants can have GERD.