  The recent series of experiments on polarized lepton-nucleon scattering have
provided a strange new twist in the story of the nucleon, some of whose aspects
are reviewed in these lectures. In the first lecture, we review some issues
arising in the analysis of the data on polarized structure functions, focusing
in particular on the importance and treatment of high-order QCD perturbation
theory. In the second lecture some possible interpretations of the ``EMC spin
effect" are reviewed, principally in the chiral soliton (Skyrmion) approach,
but also interpretations related to the axial $U(1)$ anomaly. This lecture also
discusses other indications from recent LEAR data for an $\bar{s} s$ component
in the nucleon wave function, and discusses test of a model for this component.
Finally, the third lecture reviews the implications of polarized structure
functions measurements for experiments to search for cold dark matter
particles, such as the lightest supersymmetric particle and the axion, after
reviewing briefly the astrophysical and cosmological evidence for cold dark
matter.
