Lattice QCD: A Tool for Flavor Physics

For many years, numerical lattice gauge theory has promised, some day, to provide a tool for calculating hadronic properties \emph{ab initio} from QCD. This talk argues, in three parts, that that day is here. First, we recall recent success in lattice QCD, reproducing well-measured masses, mass splittings, and light-meson decay constants. Second, we present a handful of \emph{pre}dictions, and their subsequent confirmation by experiment, designed to test our methods. Third, we survey the status and prospects of lattice-QCD calculations needed to understand flavor physics.