Bosons

Particles which do not obey the Pauli exclusion principle, for example, photons. Thus there is no limit to the number that can occupy the same region at the same time yet have the same quantum numbers; so, for example, there is no limit to the brightness of light or the loudness of sound. A boson is a particle that has integer intrinsic angular momentum (spin) measured in units of h-bar (spin =0, 1, 2, ...). All particles are either fermions or bosons. The particles associated with all the fundamental interactions (forces) are bosons. Composite particles with even numbers of fermion constituents (quarks) are also bosons.

See also: Anyon, Carrier Particle, Quark.