Heartburn is a burning feeling in the chest caused by stomach acid travelling up towards the throat (acid reflux). If it keeps happening, it may be called gastro-oesophageal reflux disease (GORD).
Burning pain or discomfort in the upper-chest and mid-chest, possibly involving the neck and throat, that may worsen when lying down.
Heartburn can have causes that aren't due to underlying disease. Examples include spicy food, alcohol, overeating or tight clothing.