In particle physics, fermions are particles which obey Fermi-Dirac statistics; they're named after Enrico Fermi. In contrast to bosons, which have Bose-Einstein statistics, only one fermion can occupy a quantum state at a given time; this's the Pauli Exclusion Principle. Thus, if more than one fermion occupies the same place in space, the properties of each fermion (for example its spin) must be different from the rest. Therefore, fermions are usually associated with matter while bosons are ofte… (More on Fermion)