Superstring extension of the standard model and gravitation

Some of the four-dimensional Superstring solutions provide a consistent framework for a Supersymmetric Unification of all interactions including gravity. A class of them extends successfully the validity of the standard model up to the string scale {\cal O}(10^{17})~GeV. We stress the importance of string corrections which are relevant for low energy {\cal O}(1)~TeV predictions of gauge and Yukawa couplings as well as the spectrum of the supersymmetric particles after supersymmetry breaking.