Here's a breakdown:

* Nuclear fission: A nuclear reaction where the nucleus of an atom is split into two or more smaller nuclei (called fission products) and a release of energy.

* Energy Release: The energy released is primarily in the form of kinetic energy of the fission products, which manifests as heat.

* Chain Reaction: Fission reactions can be self-sustaining, as the neutrons released from the fission can induce further fission reactions in neighboring atoms. This is the principle behind nuclear power plants.

Let me know if you'd like more detail on nuclear fission!