Understanding electroweak physics in the Standard Model and beyond

This contribution discusses the current status of tests of the electroweak theory and some of their essential theoretical ingredients. At medium and low energies, electroweak precision measurements are sensitive to high-scale physics through virtual loop corrections. At the energy frontier, on the other hand, the electroweak theory is tested through anomalous gauge boson couplings. It is discussed how effective field theories can be used to describe these couplings in a model-independent and theoretically well-defined way, and to correlate them to other observables. Finally, focusing on the example of W+W−W+W− production, it is demonstrated that the precise measurement of anomalous gauge boson couplings at the LHC requires good control of higher-order radiative corrections.