What causes a heartburn?

You must have felt it before. That pain, right in the middle of the chest, welling up from the stomach, burning its way like a dull leaden fire to the throat. It tastes bitter, nauseous, and is uncomfortable.

--Most people have isolated episodes of heartburn but a few suffer severe symptoms
By Paul Semugoma
You must have felt it before. That pain, right in the middle of the chest, welling up from the stomach, burning its way like a dull leaden f