What is fusion reactions in chemistry?

Fusion reactions in chemistry refer to the process in which two or more atomic nuclei come together to form a heavier nucleus, releasing a large amount of energy in the process. This process is the opposite of nuclear fission, where a heavy nucleus splits into smaller nuclei. Fusion reactions are responsible for the energy produced by the sun and other stars, and researchers are working on harnessing this process for use in nuclear fusion reactors as a potentially clean and abundant source of energy.