The form of energy that is stored in the nucleus of an atom is termed nuclear energy. This energy is released during nuclear reactions, such as fission or fusion. In fission, a heavy nucleus splits into lighter nuclei, releasing substantial energy, while fusion involves combining light nuclei to form a heavier nucleus, also releasing energy. Nuclear energy is harnessed for various applications, including electricity generation in nuclear power plants and research in nuclear physics. Understanding nuclear energy and its potential benefits and risks is essential for advancements in energy technology and safety measures.