Fission is a nuclear reaction in which the nucleus of an atom splits into two or more smaller nuclei, along with the release of energy. This process typically occurs in heavy elements like Uranium or Plutonium, and it is the principle behind nuclear power generation and atomic bombs. During fission, a neutron collides with a heavy nucleus, causing it to become unstable and break apart. The resulting fragments are often radioactive and can further release more neutrons, leading to a chain reaction. This chain reaction is harnessed in nuclear reactors to produce electricity, making fission a crucial technology in energy production.