The word lepton comes from the Greek "light" (opposite to heavy). The six leptons are all elementary, meaning they are not composed of other components.

The three charged leptons are the electron (e-), the muon (-) and the tau (-). Their antiparticles have a positive charge (+1).

The three neutral leptons are: the electron-neutrino (e), the muon-neutrino () and the tau-neutrino (t). Also the neutrinos have their antiparticles. They are different from the neutrinos through so-called inner quantum numbers.