  Wolf-Rayet (WR) stars, as they are advanced stages of the life of massive
stars, provide a good test for various physical processes involved in the
modelling of massive stars, such as rotation and mass loss. In this paper, we
show the outputs of the latest grids of single massive stars computed with the
Geneva stellar evolution code, and compare them with some observations. We
present a short discussion on the shortcomings of single stars models and we
also briefly discuss the impact of binarity on the WR populations.
