The construction and experimental foundations of the unified theory of weak and electromagnetic interactions will be reviewed. Special attention will be given to the Standard Model symmetry properties and how symmetries must be broken in order to obtain a realistic theory for the observed pattern of masses and mixing among generations and to accommodate longitudinal degrees of freedom for the vector bosons. A careful discussion of the Higgs sector, both in the perturbative and in the strongly interacting regime, will be presented. Finally, the motivations towards extensions of the standard model will be discussed.
