Theoretical Introduction to B Decays and the Soft-Collinear Effective Theory

In this talk I give an introduction to methods used to give a model independent description of QCD effects in B-decays. I discuss three useful expansions: mb/mW << 1 for the electroweak Hamiltonian, LambdaQCD/mb << 1 for Heavy Quark Effective theory, and LambdaQCD/Q << 1 for the Soft-Collinear Effective Theory where Q ~ mb is the large energy of light final state hadrons. I discuss predictions that can be made with each expansion.