Although many people call the condition where the stomach contents want to flow back up the esophagus, heartburn, it is more commonly called acid reflux. This is a disorder of the gastrointestinal tract (digestive system) and even though this condition is often known by different names, they have similar symptoms. In order to assimilate the food we eat, our stomach dissolves it with a strong acid.With this condition, acid in the stomach tries to escape up the food pathways and this is the reason for the burning pain.