B-d and B-s meson systems play a fundamental role to test and improve our understanding of Standard Model flavor dynamics. The mixing parameters Delta m(d,s) represent important constraints in the unitarity triangle analysis. Their theoretical estimates require non-perturbative calculations of B-meson decay constants and B-parameters; accurate results, recently obtained from the lattice, axe reviewed. Other phenomenologicay interesting quantities are the beauty hadron lifetime ratios and, the width differences and CP-violation parameters in Bd and B, systems. We discuss their theoretical predictions which, in the last four years, have been improved thanks to accurate lattice calculations and next-to-leading order perturbative computations.