Leptogenesis is a theoretical process in particle physics that explains the origin of the matter-antimatter asymmetry in the universe. It suggests that an imbalance between leptons, which are fundamental particles like electrons and neutrinos, and their antiparticles occurred shortly after the Big Bang. This imbalance is thought to have led to the dominance of matter over antimatter. In leptogenesis, heavy particles called Majorana neutrinos decay in a way that produces more leptons than antileptons. This process can create a surplus of leptons, which eventually contributes to the formation of baryons, the building blocks of ordinary matter. Understanding leptogenesis helps scientists explore why our universe is primarily composed of matter.