Fermions, named after Enrico Fermi, are particles which form totally-antisymmetric composite quantum states. As a result, they are subject to the Pauli exclusion principle and obey Fermi-Dirac statistics. The spin-statistics theorem states that fermions have half-integer spin.

The elementary particles which make up matter are fermions, predominantly quarks (which form protons and neutrons) and electrons. These elementary fermions are classified into two groups: leptons and quarks.

Examples of fermions:

See also: Identical particles