Gluon:

Gluon are subatomic particles that bind the fundamental particles 'quarks' together in the nucleus and so are integral to the stronger nuclear force.

Gluons have integer values of the spin quantum number. Quarks interact with one another by emitting and absorbing gluons, just as electrical subatomic particles interact through the emission or absorption of photons.Their existance was proved in 1979 with the observation of gluons by quarks in studies of high energy particle collisions.