Heart disease is the leading cause of death in the United States. Heart failure is only one of the many entities that encompass heart disease. According to National Institute of Health 5.7 million people in the United States suffered from some form of heart failure in 2009 and of these 670,000 were first events. Heart failure is not a single disease entity but "a complex clinical syndrome that can result from any cardiac disorder that impairs the ability of the ventricle to either fill properly or eject optimally. This syndrome results in a pathologic state in which the heart is unable to pump enough oxygenated blood to meet the metabolic needs of the body." The inability of the ventricle to eject properly is systolic heart failure and the inability of the ventricle to fill properly is diastolic heart failure. These are two completely different entities and will be reviewed separately. The text addresses an introduction into this topic touching on the basics of defining heart failure, addressing the two types of heart failure, going over the diagnostic tests for heart failure, addressing the classes of medications in depth to treat heart failure, and identifying the precipitating causes of heart failure.