[en] These notes are intended to help readers not familiar with particle physics in entering the domain of gauge field theory applied to the so-called standard model of strong and electroweak interactions. The introduction is considerably enlarged in order to give non specialists a general overview of present days ''elementary'' particle physics. The Glashow-Salam-Weinberg model is then treated, with the details which its unquestioned successes deserve, most probably for a long time. Finally SU(5) is presented as a prototype of these developments of particle physics which aim at a unification of all forces. Although its intrinsic theoretical difficulties and the non-observation of a sizable proton decay rate do not qualify this model as a realistic one, it has many of the properties expected from a ''good'' unified theory. In particular, it allows one to study interesting connections between particle physics and cosmology. 35 refs.