Fusion energy is the process of combining two light atomic nuclei to form a heavier nucleus, releasing a significant amount of energy in the process. This is the same reaction that powers the Sun and other stars, where hydrogen nuclei fuse to create helium. Unlike fission energy, which splits heavy atomic nuclei and produces radioactive waste, fusion has the potential to provide a cleaner and more sustainable energy source. It uses abundant fuels like hydrogen isotopes, and the byproducts are generally less harmful, making it an attractive option for future energy production.