Testing the Standard Model and its extensions with present detailed data allowsus to confront our theoretical expectations to the experimental results in amore and more precise manner. Two main lines are typically followed and arehighly complementary: the investigation of specific models and the search ofdeviations in precision observables using effective approaches. Building ourknowledge requires a solid basis from the Standard model including QCDcorrections , Higgs precision data, flavour as all these effects need to beunderstood in detail before extracting any hint of possible deviations. As someaspects of beyond standard model physics are discussed in detail in other talksI concentrate here on the main issues and on selected theoretical ideas.