Quantum Chromodynamics (QCD)
Quantum Chromodynamics (QCD) describes the dynamics of the quarks, which interact via the gluon field. QCD is based on the notion that quarks possess a charge-like property, the "color". Color charges and color currents serve as sources of electric and magnetic color fields, the gluon fields. These ideas are described by the Maxwell equations of QCD. Contrary to electrodynamics, they are nonlinear equations since the gluons themselves also carry a color charge and hence interact with each other.
QCD is new theory based on the mentioned assumptions and cannot be derived from an underlying theory. One can only construct it in such that it is compatible with phsical experiments. QCD was first formulated in a paper of Fritzsch, Gell-Mann and Leutwyler in 1973.