Heartburn is normal (and has nothing to do with the heart, except proximity). Everybody gets that burning sensation in their chest from time to time, right behind the breastbone and usually after a meal. It's when heartburn becomes a regular thing that you should become more concerned about your digestive health. Heartburn is simply a burning sensation in the esophagus and throat that comes as a result of stomach acid creeping upwards above the valve that usually closes the passage above the stomach, keeping those acids where they belong.
On the other hand, heartburn that recurs regularly may indicate gastroesophageal reflux disease (GERD) or other health conditions, in which case you should see a doctor for a diagnosis. However, occasional heartburn can be easily treated with over-the-counter or better yet home remedies.
At present, mustard and apple cider vinegar are easily the most popular home remedies for heartburn here on Earth Clinic, and you can find directions for using them to treat heartburn below. Each seems to reset the gastroesophageal junction or the stomach itself, to put an end to your symptoms. Lying on your back or bending over tends to worsen heartburn symptoms, so sitting and standing or better yet going for a walk are your best bets.