Acidity can be caused due to health problems or lifestyle patterns. Acid is produced in the stomach to break down food particles and help you digest your food. Some acid is already there, and some acid is produced by the digestion mechanism. When the food is going down the esophagus an organ called the lower esophageal sphincter opens and lets the food pass, and then immediately closes. This keeps all the acid being produced inside the stomach from rising to the esophagus. If this cap does not close on time the acid comes up and reaches the food pipe, giving you an acid reflux. This can be due to an ailment, a malfunction or consuming food in a manner that produces too much acid to be contained by the lower esophageal sphincter.