Electroweak interactions and their precision tests

These 12 lectures on electroweak interactions start with a short summary of the Glashow-Weinberg-Salam theory and then cover in detail some main subjects of present interest in phenomenology. The author concludes on the existence of a double approach in particle physics: from above and from below. From above they are, on the theory side, quantum gravity, GUT theories and cosmological scenarios. On the experimental side there are underground experiments, cosmic ray observations, satellite experiments and so on. From below, the main objectives of theory and experiment are the search of the Higgs and of signals of particles beyond the standard model