Semileptonic B Decays

Semileptonic $B$ decays provide the best experimental probes for the Cabibbo-Kobayashi-Maskawa matrix elements $V_{ub}$ and $V_{cb}$. A precise determination of the ratio $|V_{ub}/V_{cb}|$ would significantly improve the constraints on the Unitarity Triangle and provide a stringent test of the Standard-Model mechanism for $CP$ violation. In this talk, I will review recent experimental measurements of the inclusive and exclusive semileptonic $B$ decays, and discuss their interpretations.