Acid reflux disease, also known as Gastro-esophageal Reflux Disease, or GERD, is a common ailment, affecting between 5%-7% of the population. In order to understand what GERD is it is important to be familiar with how the esophagus works. A long muscular tube, the esophagus carries food and semiliquid from the mouth to the stomach. The normal adult esophagus is around ten to thirteen inches daylong and approximately an half an inch in diameter. GERD is caused by the backflow of acid from the stomach into the esophagus, usually because the lower esophageal sphincter does not close properly. When this happens finished a long period of time, the lining of this tract becomes eroded, causing discomfort and pain.