Semileptonic decays of the B mesons provide an excellent probe for the weak and strong interactions of the bottom quark. The large data samples collected at the B Factories have pushed the experimental studies of the semileptonic B decays to a new height and stimulated significant theoretical developments. We review recent progresses in this fast-evolving field, with an emphasis on the determination of the magnitude of the Cabibbo–Kobayashi–Maskawa matrix element |Vub|.
Semileptonic B decays and determination of |V_cb| at Belle