Lepton number violation refers to a process in particle physics where the total number of leptons, a type of elementary particle, changes. In standard physics, lepton number is conserved, meaning it remains constant in reactions. However, certain theories, like those involving neutrinos or Grand Unified Theories, suggest that lepton number can be violated under specific conditions. This violation could have significant implications for our understanding of the universe, particularly in explaining the matter-antimatter asymmetry observed in the cosmos. If lepton number violation occurs, it may help scientists understand the behavior of dark matter and the fundamental forces that govern particle interactions.