The Semi-Empirical Mass Formula (SEMF) is a mathematical model used in nuclear physics to estimate the mass of atomic nuclei. It combines empirical data with theoretical principles to account for various factors affecting nuclear stability, such as the number of protons and neutrons. The formula incorporates terms for volume, surface area, Coulomb repulsion, asymmetry, and pairing effects. By using the SEMF, scientists can predict the binding energy of nuclei, which helps explain phenomena like nuclear fission and fusion. This formula is particularly useful for understanding the stability of isotopes and the behavior of nuclear reactions in stars and nuclear reactors.