THEORY NEEDS FOR FUTURE e+e- COLLIDERS

New high-luminosity e(+)e(-) colliders have been proposed to perform precision measurements of electroweak and Higgs physics to scrutinize the mechanism of electroweak symmetry breaking and search for signs of new physics. The interpretation of the data from such a machine is only possible with the help of accurate theoretical calculations of the Standard Model expectations, including higher-order radiative corrections. This contribution provides an overview of the current knowledge and required improvements for our theoretical understanding of a range of key observables. Furthermore, it gives a short summary of the calculational techniques that can be leveraged to realize these improvements.