  Color transparency is the proposal that under certain circumstances the
strong interactions can be reduced in magnitude. We give a comprehensive review
of the physics, which hinges on the interface of perturbative QCD with
non--perturbative strong interactions. Color transparency is complementary to
{\it nuclear filtering}, which is the conversion of quark wave functions in
hadrons to small transverse space dimensions by interaction with a nuclear
medium. We review current approaches, including pictures based on modeling the
time evolution of hadronic wave--packets as well as the use of light cone
matrix elements. Spin plays an intrinsic role in testing and understanding the
physics and is discussed at length. We emphasize the use of data analysis
procedures which have minimal model dependence. We also review existing
experimental data and the experimental program planned at various facilities.
The subject has strong scientific complementarity and potential to make
progress in exploring hadron physics at current and future facilities.
