White dwarfs as tracers of galactic evolution

White dwarfs are the final remnants of low and intermediate mass stars. The ir evolution is essentially a cooling process that lasts for similar to 10 Gyr and allows to obtain information about the age of the Galaxy as well as about the past stellar formation rate in the solar neighborhood. We show i n this paper the state of the art of the white dwarf cooling theory and the uncertainties still remaining. We also provide some applications of the th eory of cooling white dwarfs to escrutiny the past history of the Milky Way . These applications range from an independent derivation of the past histo ry of the local star formation rate to a determination of the properties of the halo.