Relic neutrinos play an important role in the evolution of the Universe , modifying some of the cosmological observables .
We summarize the main aspects of cosmological neutrinos and describe how the precision of present cosmological data can be used to learn about neutrino properties .
In particular , we discuss how cosmology provides information on the absolute scale of neutrino masses , complementary to beta decay and neutrinoless double-beta decay experiments .
We explain why the combination of Planck temperature data with measurements of the baryon acoustic oscillation angular scale provides a strong bound on the sum of neutrino masses , 0.23Â eV at the 95 % confidence level , while the lensing potential spectrum and the cluster mass function measured by Planck are compatible with larger values .
We also review the constraints from current data on other neutrino properties .
Finally , we describe the very good perspectives from future cosmological measurements , which are expected to be sensitive to neutrino masses close the minimum values guaranteed by flavour oscillations .