  The goal of this introduction to symmetries is to present some general ideas,
to outline the fundamental concepts and results of the subject and to situate a
bit the following lectures of this school. [These notes represent the write-up
of a lecture presented at the fifth ``Seminaire Rhodanien de Physique: Sur les
Symetries en Physique" held at Dolomieu (France), 17-21 March 1997. Up to the
appendix and the graphics, it is to be published in "Symmetries in Physics",
F.Gieres, M.Kibler,C.Lucchesi and O.Piguet, eds. (Editions Frontieres, 1998).]
