A lepton is a building block of matter. Several leptons exists, including electrons, muons, tau particles and neutrinos. Leptons differ in characteristics with neutrinos being the most exotic.
The electron is considered a fundamental particle. It follows Pauli's Exclusion principle, meaning it cannot have the same quantum number or have the same energy state as another electron. Its antiparticle is the positron, which carries an opposite charge. The muon decays to form either an electron or positron. The tau is the largest of leptons and has a mass that is 3490 times more at rest than the electron and 17 times more than a muon.