  Light-Front Holography, a remarkable feature of the AdS/CFT correspondence,
maps amplitudes in anti-de Sitter (AdS) space to frame-independent light-front
wavefunctions of hadrons in physical space-time. The model leads to an
effective confining light-front QCD Hamiltonian and a single-variable
light-front Schrodinger equation which determines the eigenspectrum and the
light-front wavefunctions of hadrons for general spin and orbital angular
momentum. The coordinate z in AdS space is identified with a Lorentz-invariant
coordinate zeta which measures the separation of the constituents within a
hadron at equal light-front time and determines the off-shell dynamics of the
bound-state wavefunctions and the fall-off in the invariant mass of the
constituents. The soft-wall holographic model, modified by a positive-sign
dilaton metric, leads to a remarkable one-parameter description of
nonperturbative hadron dynamics -- a semi-classical frame-independent first
approximation to the spectra and light-front wavefunctions of meson and
baryons. The model predicts a Regge spectrum of linear trajectories with the
same slope in the leading orbital angular momentum L of hadrons and the radial
quantum number n. The hadron eigensolutions projected on the free Fock basis
provides the complete set of valence and non-valence light-front Fock state
wavefunctions which describe the hadron's momentum and spin distributions
needed to compute measures of hadron structure at the quark and gluon level.
The effective confining potential also creates quark- antiquark pairs. The
AdS/QCD model can be systematically improved by using its complete orthonormal
solutions to diagonalize the full QCD light-front Hamiltonian or by applying
the Lippmann-Schwinger method to systematically include the QCD interaction
terms. A new perspective on quark and gluon condensates is also presented.
