Angina is a type of chest pain caused by an inadequate supply of oxygen to certain muscles in the heart. It is usually a symptom of an underlying heart condition, usually coronary heart disease. It typically presents as a feeling of squeezing or pressure in the chest, though pain may also extend to or be centered in the back, neck or jaw. There are two major types of angina: stable angina, which occurs at regular and predictable intervals, and unstable angina, which does not follow any pattern of presentation. It can be controlled with medication, though patients should also be thoroughly examined for any evidence of underlying heart conditions.