Quarks and gluons are the building blocks of protons and neutrons, which in turn are the building blocks of atomic nuclei. Scientists' current understanding is that quarks and gluons are indivisible—they cannot be broken down into smaller components.

How did quarks and gluons form?

For a few millionths of a second, shortly after the Big Bang, the universe was filled with an astonishingly hot, dense soup made of all kinds of particles moving at near light speed. This forms a miniscule fireball in which everything “melts” into a quark-gluon plasma. ...

What is the difference between a quark and a gluon?

In classical QCD quarks are the fermionic components of hadrons (mesons and baryons) while the gluons are considered the bosonic components of such particles. The gluons are the force carriers, or bosons, of the QCD color force, while the quarks by themselves are their fermionic matter counterparts.