Heart disease is the leading cause of death worldwide. It is caused by atherosclerosis, a buildup of fatty plaques in the coronary arteries that supply the heart with blood. Risk factors include age, family history, high cholesterol, smoking, high blood pressure, diabetes, obesity, physical inactivity, and excessive alcohol consumption. Preventing heart disease involves maintaining a healthy diet low in saturated fat and cholesterol, exercising regularly, not smoking, monitoring cholesterol and other health numbers, and treating conditions like high blood pressure and diabetes. Making lifestyle changes and managing risk factors can significantly reduce the chances of developing heart disease.