Hadronization
In particle physics, hadronization is the process of the formation of hadrons out of quarks and gluons. This occurs after high-energy collisions in a particle collider in which free quarks or gluons are created. Due to confinement, these cannot exist individually. They combine with quarks and antiquarks spontaneously created from the vacuum to form hadrons. The details of this process are not yet understood.
Hadronization also occured shortly after the big bang when the quark-gluon plasma cooled to the temperature below which free quarks and gluons cannot exist (about 170 MeV). The quarks and gluons then combined into hadrons.