Lepton

A lepton is a fermion, meaning that it is an elementary particle with half-integer spin. Leptons consist of several types of electron-like particles and neutrinos. There are three known electron-like particles; the electron, muon and the tau. The neutrinos include the electron-neutrino, the muon-neutrino and the tau-neutrino. Along with quarks, leptons form the fundamental particles of matter.