What is nuclear fusion? - Leaving Cert Physics - Question i - 2008

Nuclear fusion is the process in which two light atomic nuclei combine to form a heavier nucleus. This process occurs under extremely high temperatures and pressures, such as those found in the cores of stars, including our sun.

During fusion, a significant amount of energy is released as a result of the mass-to-energy conversion, expressed by the famous equation: $E=mc^2$

In practical terms, nuclear fusion powers the sun and other stars, producing light and heat. The energy emitted comes from the binding energy of the resultant nucleus, which is greater than that of the individual lighter nuclei being fused. This is a fundamental process that fuels stellar life cycles and contributes to the energy we receive from the sun.