  The pairing and superfluid phenomena in a two-component ultracold atomic
Fermi gas is an analogue of Cooper pairing and superconductivity in an electron
system, in particular, the high $T_c$ superconductors. Owing to the various
tunable parameters that have been made accessible experimentally in recent
years, atomic Fermi gases can be explored as a prototype or quantum simulator
of superconductors. It is hoped that, utilizing such an analogy, the study of
atomic Fermi gases may shed light to the mysteries of high $T_c$
superconductivity. One obstacle to the ultimate understanding of high $T_c$
superconductivity, from day one of its discovery, is the anomalous yet
widespread pseudogap phenomena, for which a consensus is yet to be reached
within the physics community, after over 27 years of intensive research
efforts. In this article, we shall review the progress in the study of
pseudogap phenomena in atomic Fermi gases in terms of both theoretical
understanding and experimental observations. We show that there is strong,
unambiguous evidence for the existence of a pseudogap in strongly interacting
Fermi gases. In this context, we shall present a pairing fluctuation theory of
the pseudogap physics and show that it is indeed a strong candidate theory for
high $T_c$ superconductivity.
