  The light-front (LF) quantization of QCD in light-cone gauge has a number of
remarkable advantages, including explicit unitarity, a physical Fock expansion,
the absence of ghost degrees of freedom, and the decoupling properties needed
to prove factorization theorems in high momentum transfer inclusive and
exclusive reactions. We present a systematic study of LF-quantized gauge theory
following the Dirac method and construct the Dyson-Wick S-matrix expansion
based on LF-time-ordered products. The free theory gauge field is shown to
satisfy the Lorentz condition as an operator equation as well as the light-cone
gauge condition. Its propagator is found to be transverse with respect to both
its four-momentum and the gauge direction. The interaction Hamiltonian of QCD
can be expressed in a form resembling that of covariant theory, except for
additional instantaneous interactions which can be treated systematically. The
renormalization constants in YM theory are shown to satisfy the identity
$Z_1=Z_3$ at one loop order. The QCD $\beta$ function computed in the
noncovariant light-cone gauge agrees with that known in the conventional
framework. Some comments on the relationship of our LF framework, with the
doubly transverse gauge propagator, to the analytic effective charge and
renormalization scheme defined by the pinch technique, the unitarity relations
and the spectral representation are also made. LF quantization thus provides a
consistent formulation of gauge theory, despite the fact that the hyperplanes
$x^{\pm}=0$ used to impose boundary conditions constitute characteristic
surfaces of a hyperbolic partial differential equation.
