The properties of white dwarfs in cataclysmic variables:: A complex interplay with the accretion process

I review our current knowledge of the fundamental properties of white dwarfs in cataclysmic variables. Accretion affects the general properties of the white dwarfs in these systems, such as mass, rotational velocity, temperature, and chemical abundances, on various timescales. The consequences are, e.g., secular mass erosion, spin-up due to angular momentum accretion, an inhomogeneous temperature distribution over the white dwarf surface, short-term heating and cooling of the white dwarf envelope in response to changes in the accretion rate, retarded core cooling compared to non-accreting white dwarfs, and enrichment of the white dwarf photosphere by accretion of heavy elements.