Acid reflux is a very common condition that causes acid from your stomach to flow back up into your oesophagus and towards your mouth. People suffering from acid reflux normally experience high levels of discomfort and pain due to this problem. The acid itself can also cause damage to the tissue in the throat; stomach acid being extremely acidic and capable of corroding most metals. Serious cases of acid reflux can actually be life threatening - but only when left untreated for many, many years.
The common name acid reflux (or heartburn) is just a laymans name for Gastro Oesophageal Reflux Disease (GERD for short) but most people find it easier to explain and pronounce acid reflux than the rather long winded Gastro Oesophageal Reflux Disease