1.2 Bosons 1.3 Hypothetical particles 2 Composite particles 2.1 Hadrons 2.1.1 Baryons (fermions) 2.1.2 Mesons (bosons) Fermion (named after Enrico Fermi )   is any particle which obeys the Fermi–Dirac statistics (and follows the Pauli exclusion principle ). Fermions contrast with bosons which obey Bose–Einstein statistics . A quark is an