The globular cluster system of M31

Globular clusters are studied for their intrinsic properties as well as for the information they give on their parent galaxy. No less than 300 articles address the globular cluster system of M31. I briefly mention here the topics tackled over the years and will come back in more detail to some of them below: their total number and specific frequency, their stellar population: age and metallicity, the distance to M31, the relation between the level of the horizontal branch and metallicity, the search for novae, the bulge/disc/halo cluster properties, the radial distribution of their properties, their luminosity function, their kinematics, dynamics, their true shape, ellipticity, tidal radii, effective radii, the absorption law in M31, the mass and mass distribution of M31, the scenario for the formation of M31. For all these topics, comparisons with our Galaxy and galaxies in the Local Group are usually conducted.