Binding energy is the energy required to hold the components of a system together. In the context of atomic nuclei, it refers to the energy needed to separate protons and neutrons from each other. A higher binding energy indicates a more stable nucleus, as it means that more energy is required to break it apart. In nuclear physics, binding energy can be calculated using the mass defect, which is the difference between the mass of the individual nucleons and the mass of the nucleus. This concept is crucial for understanding processes like nuclear fission and fusion, where energy is released when nuclei combine or split apart, respectively.