Metal binding refers to the process by which certain molecules, known as ligands, attach themselves to metal ions. This interaction is crucial in various biological and chemical systems, as it can influence the behavior and reactivity of the metal. Common examples of metal-binding ligands include proteins, enzymes, and small organic molecules. In biological systems, metal binding plays a vital role in processes such as oxygen transport and electron transfer. For instance, the protein hemoglobin binds to iron to transport oxygen in the blood. Understanding metal binding is essential for fields like biochemistry and environmental science, where it affects everything from nutrient cycling to pollution management.