In 1971 Gell-Mann and I introduced the color quantum number of the quarks. One year later the exact color symmetry group was interpreted as the gauge group of a new gauge theory, quantum chromodynamics. The self-coupling of the gluons leads to the property of asymptotic freedom and to the confinement of the quarks and gluons. The hadrons are color singlets. At DESY and at LEP the quarks and gluons have been observed indirectly at high energies as hadronic jets. Today QCD is regarded as the correct theory
of the strong interactions and of the nuclear force.

NOTES

Visiting Professor with the BKC excellence program