Quantum chromodynamics, QCD, is the theory of strong interactions in the standard model. QCD explains the strong interaction as an interactions between quarks and gluons.
The fundamental theory of strong nuclear interactions between hadrons such as the proton, the neutron, the pi and K mesons and even hyperons. It is based on the fact that they are all made up of quarks, fractionally charged particles. These exist as various species called flavours and carry a specific 'charge' of the strong interaction called colour. Like quantum electrodynamics, QCD satisfies the rules of quantum mechanics and relativity and has a structure similar to so-called gauge theory.
The list of important contributors to the elaboration of this theory is vast, the foremost being Gell-Mann, Gross, Politzer,'t Hooft and Wilczek, all Nobel prize winners.