These lecture notes give an introduction to the algebraic renormalization of the Standard Model. We start with the construction of the tree approximation and give the classical action and its defining symmetries in functional form. These are the Slavnov-Taylor identity, Ward identities of rigid symmetry and the abelian local Ward identity. The abelian Ward identity ensures coupling of the electromagnetic current in higher orders of perturbation theory, and is the functional form of the Gell-Mann-Nishijima relation. In the second part of the lectures we present in simple examples the basic properties of renormalized perturbation theory: scheme dependence of counterterms and the quantum action principle. Together with an algebraic characterization of the defining symmetry transformations they are the ingredients for a scheme independent unique construction of Green's functions to all orders of perturbation theory.