Light nuclei move "up" the curve to become more stable by fusing together. This process powers stars like our Sun.
Beyond iron, the binding energy per nucleon gradually decreases. This happens because the repulsive electrostatic force between protons begins to overcome the short-range strong nuclear force. Saturation Region: Between mass numbers , the binding energy is relatively constant (around The curve of binding energy
The shape of the curve dictates how we can extract energy from the atom: Light nuclei move "up" the curve to become