  A fundamental goal in QCD is to understand the non-perturbative structure of
hadrons at the amplitude level--not just the single-particle flavor, momentum,
and helicity distributions of the quark constituents, but also the multi-quark,
gluonic, and hidden-color correlations intrinsic to hadronic and nuclear
wavefunctions. A natural calculus for describing the bound-state structure of
relativistic composite systems in quantum field theory is the light-front Fock
expansion which encodes the properties of a hadrons in terms of a set of
frame-independent n-particle wavefunctions. Light-front quantization in the
doubly-transverse 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. A number
of applications are discussed in these lectures, including semileptonic B
decays, two-photon exclusive reactions, and deeply virtual Compton scattering.
The relation of the intrinsic sea to the light-front wavefunctions is
discussed. A new type of jet production reaction, "self-resolving diffractive
interactions" can provide direct information on the light-front wavefunctions
of hadrons in terms of their quark and gluon degrees of freedom as well as the
composition of nuclei in terms of their nucleon and mesonic degrees of freedom.
