The Determination of || and QCD Sum Rules in Hqet

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I review recent developments in Heavy Quark Effective Theory (HQET) that lead to an almost model--independent determination of the || element of the Cabibbo--Kobayashi--Maskawa matrix from exclusive semileptonic B D⁽*⁾ decays. In particular, I compare the theoretical uncertainties in the B D*ℓν and the B Dℓν decay modes. I discuss the applications of QCD sum rules within HQET to semileptonic heavy meson decays and give predictions for the form factors measurable in B D⁽*⁾ℓν decays.