Nuclear fusion occurs when two atomic nuclei combine to create a heavier nucleus, releasing a large amount of energy in the process. This process is what powers the sun and other stars in the universe. Scientists have been working on creating a controlled fusion reaction on Earth to harness this energy as a new, clean source of power. While progress has been made, there are still many challenges to overcome before this technology can be fully realized. However, the potential benefits of fusion energy make it an attractive area of research.