  Precision electroweak data allow one to test the standard model, constrain
its parameters, and search for the effects of some kinds of new physics. The
results of the most recent data from LEP, SLC, and elsewhere are described, as
are their predictions for $m_t$, $M_H$, and $\alpha_s$. The implications for
the two major classes of extensions of the standard model,
supersymmetry/unification and compositeness, are described.
