  In this article, we discuss the identity and indistinguishability of quantum
systems and the consequent need to introduce an extra postulate in Quantum
Mechanics to correctly describe situations involving indistinguishable
particles. This is, for electrons, the Pauli Exclusion Principle, or in
general, the Symmetrization Postulate. Then, we introduce fermions and bosons
and the distributions respectively describing their statistical behaviour in
indistinguishable situations. Following that, we discuss the spin-statistics
connection, as well as alternative statistics and experimental evidence for all
these results, including the use of bunching and antibunching of particles
emerging from a beam splitter as a signature for some bosonic or fermionic
states.
