The inferior vena cava is a large vein in the human body that carries deoxygenated blood from the lower half back to the heart. It collects blood from the lower limbs, pelvis, and abdomen, ensuring that this blood returns to the right atrium of the heart for reoxygenation in the lungs. This vein is one of the two main vena cavae, the other being the superior vena cava, which drains blood from the upper body. The inferior vena cava is crucial for maintaining proper blood circulation and overall cardiovascular health.