  In this thesis, we have presented some of the aspects of light-front (LF)
field theory through their successful application in the Deep Inelastic
Scattering (DIS). We have developed a LFQCD Hamiltonian description of the DIS
structure functions starting from Bjorken-Johnson-Low limit of virtual forward
Compton scattering amplitude and using LF current commutators. We worked in the
LF gauge $A^+=0$ and used the old-fashioned LFQCD perturbation theory in our
calculations. The importance of our work are summarized below.
  Our approach shares the intution of parton model and addresses directly the
structure functions, which are experimental objects, instead of its moments as
in OPE method. Moreover, it can potentially incorporate the non-perturbative
contents of the structure functions as we have demonstrated by introducing a
new factorization scheme.
  In the context of nucleonic helicity structure, the well known gauge fixed LF
helicity operator is shown to provide consistent physical information and helps
us defining new relevant structure functions. The anomalous dimensions relevant
for the $Q^2$-evolution of such structure functions are calculated.
  Our study is important in establishing the equivalance of LF field theory and
the usual equal-time one through perturbative calculations of the dressed
parton structure functions reproducing the well known results. Also the
importance of Gallilean boost symmetry in understanding the correctness of any
higher order calculation using ($x^+$)-ordered LFQCD perturbation theory are
emphasized.
