This document provides an overview of heart failure, including its pathophysiology, types, clinical presentation, investigations, and management. Heart failure occurs when the heart cannot pump enough blood to meet the body's needs and can develop due to conditions that weaken the heart such as heart attacks or high blood pressure. Symptoms depend on whether the left side, right side, or both sides of the heart are affected. Management involves treating the underlying cause, reducing symptoms through medications, lifestyle changes, and addressing complications.