This write-up of lectures given at TASI 2020 provides an introduction into precision tests of the electroweak Standard Model. The lecture notes begin with a hands-on review of the (on-shell) renormalization procedure, and subsequently highlight a few subtleties that occur in the renormalization of a theory with electroweak symmetry breaking and massive gauge bosons. After that a set of typical electroweak precision observables is introduced, as well as a range of input parameter measurements that are needed for making predictions within the Standard Model. Finally, it is discussed how comparisons of the electroweak precision observables between experiment and theory can be used to stress-test the Standard Model and probe new physics.