Bosons

"In particle physics, Boson is a subatomic particle with integer spin (i.e., angular momentum in quantum-mechanical units of 0, 1, etc.) that is governed by Bose-Einstein statistics. Bosons include mesons (e.g., pions and kaons), nuclei of even mass number (e.g., helium-4), and the particles required to embody the fields of quantum field theory (e.g., photons and gluons). Bosons differ significantly from a group of subatomic particles known as fermions in that there is no limit to the number that can occupy the same quantum state. This behaviour gives rise, for example, to the remarkable properties of helium-4 when it is cooled to become a superfluid."

"Bosons contrast with fermions, which obey Fermi–Dirac statistics. Two or more fermions cannot occupy the same quantum state (see Pauli exclusion principle)."

"Since bosons with the same energy can occupy the same place in space, bosons are often force carrier particles. In contrast, fermions are usually associated with matter (although in quantum physics the distinction between the two concepts is not clear cut)."

"Bosons may be either elementary, like photons, or composite, like mesons."

"All observed bosons have integer spin, as opposed to fermions, which have half-integer spin. This is in accordance with the spin-statistics theorem, which states that in any reasonable relativistic quantum field theory, particles with integer spin are bosons, while particles with half-integer spin are fermions."