  I begin by briefly reviewing various experimental results on the pseudogap
phenomena in underdoped cuprates. I argue that, taken together, all of these
lead to a picture of singlet pairing above $T_c$. I then explore the idea that
the pseudogap is a normal state precursor of the superconducting gap due to
local, dynamic pairing correlations in a state without long range phase
coherence. Early work on simple model systems which exhibit pseudogap anomalies
in the normal state of 2D superconductors in a low density, small pair size
regime is reviewed and critically re-examined in view of more recent
developments. I also describe recent studies of how the underlying d-wave
superconducting ground state affects the anisotropy of the pseudogap and the
destruction of the Fermi surface.
