Helium-3 is a rare isotope of helium that contains two protons and one neutron. Unlike the more common helium-4, which has two neutrons, helium-3 is lighter and has unique properties. It is primarily produced through the decay of tritium, a radioactive isotope of hydrogen, and can also be found in small amounts in natural gas deposits and lunar regolith. This isotope has gained interest for its potential use in nuclear fusion as a clean energy source. When fused with deuterium, another hydrogen isotope, helium-3 can produce energy without generating harmful radiation or long-lived radioactive waste, making it a promising candidate for future energy solutions.