  I discuss several aspects of strings as unified theories. After recalling the
difficulties of the simplest supersymmetric grand unification schemes I
emphasize the distinct features of string unification. An important role in
constraining the effective low energy physics from strings is played by
$duality$ symmetries. The discussed topics include the unification of coupling
constants (computation of $\sin ^2\theta _W$ and $\alpha _s$ at the weak
scale), supersymmetry breaking through gaugino condensation, and properties of
the induced SUSY-breaking soft terms. I remark that departures from
universality in the soft terms are (in contrast to the minimal SUSY model)
generically expected.
