Lepton-flavour-violating decays refer to particle decays that violate the conservation of lepton flavour. In the Standard Model of particle physics, lepton flavour is conserved, meaning that the number of electrons, muons, and tau particles are separately conserved in a particle interaction. However, in certain extensions of the Standard Model, lepton-flavour-violating decays are possible. Studying lepton-flavour-violating decays can provide valuable insights into physics beyond the Standard Model, as these decays are not allowed within the framework of the Standard Model. By searching for and studying these decays, researchers hope to uncover new physics phenomena and potentially explain some of the unanswered questions in particle physics, such as the origin of neutrino masses and the matter-antimatter asymmetry in the universe. Experimental efforts to search for lepton-flavour-violating decays are ongoing at particle colliders and other high-energy physics experiments.