  A brief review of the Witten-Sakai-Sugimoto model is given, which is a
top-down holographic model of low-energy QCD with chiral quarks derived from
type-IIA superstring theory. The main predictions of the model, in particular
concerning meson spectra, the gluon condensate, the QCD string tension, the
mass of the $\eta'$ and of baryons are discussed and compared quantitatively
with available experimental and/or lattice results. Then some recent results of
potential interest to the physics program at the future FAIR facility are
presented: The spectrum of glueballs and their decay rates into pions, and the
phase diagram of QCD at finite temperature, density, and magnetic field
strength.
