In the setting of strict wonderful varieties we answer positively to Luna's
conjecture, saying that wonderful varieties are classified by combinatorial
objects, the so-called spherical systems. In particular, we prove that strict
wonderful varieties are mostly obtained from symmetric spaces, spherical
nilpotent orbits or model spaces. To make the paper self-contained as much as
possible, we shall gather some known results on these families and more
generally on wonderful varieties.Comment: 39 pages; final version to appear in Annales Inst. Fourie