Heavy Quark Effective Theory (HQET) is reviewed and applied to extracting the fundamental parameters of the Standard Model from experimental data. The main focus is on precision measurements of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb|, and the charm and bottom quark masses mc and mb. We discuss the model-independent extraction of |Vcb| from the B → D*lv decay rate and show that the corresponding theoretical uncertainties, although small, cannot be further reduced. The theory of the inclusive B → Xclv decay is described and then used to extract |Vcb|, mc, and mb from the available data. We also determine the HQET parameters Λ and λ1 which appear in the expressions for the heavy meson decay rates and the relations between the meson and quark masses. At present, the accuracy of the inclusive measurement of |Vcb| is comparable to that from the exclusive B → D*lv decay, but could be improved if the bottom quark mass mb were known better. We show how this could be accomplished by measuring the photon spectrum in the rare inclusive B → Xsγ decay.