The Oxygen Dissociation Curve illustrates how hemoglobin in red blood cells binds to oxygen. It shows the relationship between the partial pressure of oxygen and the percentage of hemoglobin saturated with oxygen. As oxygen levels increase, hemoglobin binds more oxygen, but this binding becomes less efficient at very high oxygen levels. The curve is typically sigmoidal (S-shaped), indicating that once some oxygen is bound, hemoglobin's affinity for additional oxygen increases. This cooperative binding allows for efficient oxygen uptake in the lungs and release in tissues, ensuring that cells receive the oxygen they need for metabolism.