Demystifying lattice QCD computations of alpha_s

Lattice QCD permits the strong coupling constant alpha_s to be determined from the masses and decay constants of the light hadrons. The precision achieved in these computations is competitive with the one of the world average of the experimental measurements of the coupling and is likely to improve in the coming years. In this colloquium, the aim is to explain, in terms that do not assume any expert knowledge of lattice QCD, how exactly the hadronic regime of QCD is connected to high-energy collider physics and how the lattice calculations of alpha_s proceed.