Hemoglobin is a vital protein found in red blood cells that is responsible for transporting oxygen from the lungs to the rest of the body. It binds to oxygen molecules, allowing them to be carried through the bloodstream, which is essential for cellular respiration and energy production. In addition to oxygen transport, hemoglobin also plays a role in carrying carbon dioxide back to the lungs for exhalation. Its structure allows it to change shape, which is crucial for its function in oxygen uptake and release, making it a key player in maintaining the body's overall health.