A brief introduction to QCD and asymptotic freedom is given. A new method to avoid scheme and scale ambiguities in perturbative QCD predictions is discussed. A detailed discussion of light-cone perturbation theory and the Fock state expansion of hadronic wavefunctions is given. The QCD equation of motion is also discussed. Measures of the hadronic wavefunction (form factors, magnetic moments, etc.), and the QCD analysis of high momentum transfer exclusive processes are discussed. It is also shown how meson distribution amplitudes can be measured in .gamma gamma. .-->. M anti M reactions. The connection of the Fock state basis to leading and higher twist contributions to deep inelastic scattering is given. How many different QCD processes are interelated through the hadronic Fock states is discussed, and a novel type of QCD subprocess - direct coupled hadron-induced reactions is considered. A new prediction for the proton form factor is also given. Also, a simple phenomenology of hadron wavefunctions is introduced, and present constraints on the form and normalization of the valence meson and nucleon Fock states are discussed. An important conclusion is that the valence Fock state as defined at equal time or the light cone appears to have a significantly smaller radius than that of the physical hadron; higher Fock states thus play an essential role in low momentum transfer phenomenology. Applications to quark jet diffraction excitation and the hidden heavy quark Fock state structure of hadrons are also discussed. 83 references. (WHK).