GERD is a chronic digestive disorder where stomach acids back up into the oesophagus pipe. Oesophagus pipe in usual conditions carries food from your throat to your stomach and when food reaches the stomach the lower end of the food pipe called a lower esophageal sphincter (LES) closes avoiding the food and stomach acidic juices from moving back to the pipe. When this sphincter does not close properly or relaxes abnormally, the food returns to the food pipe (acid reflux) and irritates its lining which further causes symptoms like heartburn. When you experience this type of acid reflux or heartburn frequently more than twice in a week, then it is considered to be GERD.