This paper is an extended and updated version of the reviews by Giovannelli (2008) and Giovannelli
& Sabau-Graziati (2015a). In this paper we review cataclysmic variables (CVs) discussing
several hot points about the renewing interest of today astrophysics about these sources. We
will briefly discuss also about classical and recurrent novae, as well as the intriguing problem of
progenitors of the Type Ia supernovae.
However, the bulk of this paper consists in our attempt of studying CVs from the point of view of
the magnetic field intensity (B) at the surface of their white dwarfs.
Because of limited length of the paper and our knowledge, this review does not pretend to be
complete. However, we would like to demonstrate that the improvement on knowledge of the
physics of our Universe is strictly related also with the multifrequency behaviour of CVs, which
apparently in the recent past lost to have a leading position in modern astrophysics.