  Amidst all candidates of physics beyond the Standard Model, string theory
provides a unique proposal for incorporating gauge and gravitational
interactions. In string theory, a four-dimensional theory that unifies quantum
mechanics and gravity is obtained automatically if one posits that the
additional dimensions predicted by the theory are small and curled up, a
concept known as compactification. The gauge sector of the theory is specified
by the topology and geometry of the extra dimensions, and the challenge is to
reproduce all the features of the Standard Model of Particle Physics from them.
We review the state-of-the-art in reproducing the Standard Model from string
compactifications, together with the lessons drawn from this fascinating quest.
We describe novel scenarios and mechanisms that string theory provides to
address some of the Standard Model puzzles, as well as the most frequent
signatures of new physics that could be detected in future experiments. We
finally comment on recent developments that connect, in a rather unexpected
way, the Standard Model with Quantum Gravity, and that may change our field
theory notion of naturalness.
