  I review progress in measurements of the dynamic spin susceptibility in the
normal state which yield a new phase diagram and discuss microscopic
calculations which yield qualitative, and in many cases, quantitative agreement
with the measured changes in the quasiparticle, transport, magnetotransport,
and optical properties of the cuprate superconductors as one varies doping and
temperature provided one describes the systems as nearly anti-ferromagnetic
Fermi liquids in which the effective magnetic interaction between planar
quasiparticles mirrors the dynamic spin susceptibility measured in NMR and INS
experiments. Together with the demonstration that the NAFL pairing potential
leads inexorably to a d_x2-y2,pairing state, this work provides a "proof of
concept" for the NAFL description of high Tc materials. I review Eliashberg
calculations of the mean-field behavior found in overdoped systems and discuss
the extent to which the crossovers to pseudoscaling and pseudogap behavior
found in the effective magnetic interaction and quasiparticle behavior in the
optimally doped and underdoped systems may be derived microscopically. I
conclude with a tentative scenario for the dependence of Tc on doping level and
imperfections in different systems.
