2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/50844We briefly review attempts to construct string theories that yield the standard model, concentrating on models with a geometric interpretation. Calabi-Yau compactifications are discussed in the context of both the weakly coupled heterotic string and the strongly coupled version, heterotic M-theory. Similarly, we consider orbifold compactifications of weakly coupled heterotic theory and of Type II theories in the presence of D-branes. The latter allows a "bottom-up" construction that so far seems the most natural and direct route to the standard model.21 pages, LaTeX file, Based on a talk given by D. Bailin, at the first Cairo International Conference on High Energy Physics, (CICHEP 2001), Jan.2001. To be published in the proceedingsHigh Energy Physics - Theorytext