This is an overview of quark flavor physics as presented in a plenary talk at Lattice 2023. In the first part, I discuss the main processes and lattice-QCD inputs used to determine the Wolfenstein parameters of the Cabibbo-Kobayashi-Maskawa matrix. In the second part, I review selected further processes that are being used to search for physics beyond the Standard Model. New results presented at Lattice 2023 are referenced throughout, but detailed discussions are limited to selected work published prior to the conference. QED corrections, inclusive decays on the lattice, and processes involving hadronic resonances are not discussed in detail here, as they were covered in other plenary talks at Lattice 2023 and Lattice 2022.