Precision cosmology and neutrino properties

I give an overview of what we do know from astrophysical data about some of neutrino properties and their role in cosmology. In particular, I focus on the number of effective neutrino species, active neutrino mass bounds and constraints on neutrino–antineutrino asymmetries. Finally, I also discuss the possibility of a non negligible abundance of eV mass scale sterile neutrino species in the early universe.