While speculative, string theory remains the best motivated and most encompassing approach to extending the Standard Model and answering questions the Standard Model does not address. The phenomenological aspects of string theories have received renewed attention in recent years. String theory incorporates mechanisms to stabilize the hierarchy, and generate electroweak symmetry breaking; it contains possible explanations of gauge coupling unification, light neutrinos, inflation and baryogenesis, as well as the dark matter and dark energy. String models can address flavour issues including the number of families, rare or forbidden decays, the values of quark and lepton masses (including neutrino masses), and CP violation. String phenomenology tries to make the connection between the results of formal string theory at high energy scales and the physics of the world around us, which is accessible to experiments