Quantum Chromodynamics (QCD) is the physical theory describing one of the fundamental forces, the strong interaction. It was first proposed in the early 1970s by David Politzer and by Frank Wilczek and David Gross. It uses quantum field theory to describe the interaction of quarks and gluons.
According to this theory, there is an SU(3) gauge group and that the quarks are SU(3) triplet Dirac fermion fieldss. QCD is a non-perturbative theory due to effects like confinement, fermion condensates and instantons.
Most theoretical work on QCD is done with lattice models.