Heart failure is a clinical syndrome where the heart is unable to pump sufficiently to maintain blood flow to meet the body's needs. It can be caused by structural or functional defects in the heart. The most common causes are coronary artery disease, high blood pressure, and diabetes. While it affects about 2% of adults globally, the risk increases to 6-10% for those over age 65. Treatment involves controlling underlying causes, removing precipitating factors, and managing symptoms through diuretics, ACE inhibitors, beta blockers, and other medications.