Heart failure (HF) is a condition where the heart cannot pump blood effectively to meet the body's needs, often distinguished into left-sided and right-sided failures with different symptoms and causes. Left-sided heart failure leads to pulmonary congestion and edema, while right-sided failure causes systemic edema and increased venous pressure. Diagnosis involves clinical signs, physical examination, and imaging, with treatment options including diuretics, vasodilators, and drugs to enhance myocardial function.