Pericardial fluid is a crucial component of the pericardium, a double-layered sac that surrounds the heart. This clear, serous fluid serves as a lubricant, facilitating smooth and frictionless movement between the layers of the pericardium during the cardiac cycle. Composed primarily of water, electrolytes, and proteins, pericardial fluid acts as a protective cushion for the heart, preventing friction-related damage and ensuring optimal cardiac function. Any imbalance in the production or absorption of pericardial fluid can lead to medical conditions such as pericardial effusion, underscoring the vital role this fluid plays in maintaining the integrity and functionality of the heart.