CP Violation in B Decays: The Standard Model and Beyond

We review the subject of CP violation in $B$ decays in the Standard Model (SM) and beyond the SM. We describe some of the present most promising ways of testing the Cabibbo-Kobayashi-Maskawa (CKM) origin of CP violation through a determination of the three angles of the CKM matrix unitarity triangle. Other sources of CP nonconservation violate SM constraints on the unitarity triangle. We show that different models of physics beyond the SM can be distinguished by combining their effects in CP asymmetries and in rare flavor-changing $B$ decays.