This process releases a tremendous amount of energy, which is what powers the sun and other stars. Here's why:

* Binding energy: Nuclei are held together by the strong nuclear force. Heavier nuclei have more binding energy per nucleon (proton or neutron) than lighter nuclei.

* Mass defect: When two lighter nuclei fuse, a tiny amount of their mass is converted into energy. This energy is released, according to Einstein's famous equation, E=mc².

Examples of nuclear fusion:

* The Sun: Hydrogen nuclei (protons) fuse to form helium, releasing energy in the form of light and heat.

* Hydrogen bombs: Fusion reactions are used in hydrogen bombs to create devastating explosions.

Let me know if you'd like to learn more about nuclear fusion!