Spin–charge separation is one of the most unusual manifestations of the concept of quasiparticles. This property is counterintuitive, because neither the spinon, with zero charge and spin half, nor the chargon, with charge minus one and zero spin, can be constructed as combinations of the electrons, holes, phonons and photons that are the constituents of the system. It is an example of fractionalization, the phenomenon in which the quantum numbers of the quasiparticles are not multiples of those of the elementary particles, but fractions.