  Supersymmetric gauge theories have had a significant impact on our
understanding of QCD and of field theory in general. The phases of N=1
supersymmetric QCD (SQCD) are discussed, and the possibility of similar phases
in non-supersymmetric QCD is emphasized. It is described how duality in SQCD
links many previously known duality transformations that were thought to be
distinct, including Olive-Montonen duality of N=4 supersymmetric gauge theory
and quark-hadron duality in (S)QCD. A connection between Olive-Montonen duality
and the confining strings of Yang-Mills theory is explained, in which a picture
of confinement via non-abelian monopole condensation -- a generalized dual
Meissner effect -- emerges explicitly. Similarities between supersymmetric and
ordinary QCD are discussed, as is a non-supersymmetric QCD-like ``orbifold'' of
N=1 Yang-Mills theory. I briefly discuss the recent discovery that gauge
theories and string theories are more deeply connected than ever previously
realized. Specific questions for lattice gauge theorists to consider are raised
in the context of the first two topics. (Published in ``At the Frontier of
Particle Physics: Handbook of QCD'', M. Shifman, editor)
