  In the first part of this article, we review the observational evidence for
spirals in the accretion discs of cataclysmic variables. It is shown that with
the increasing amount of data available, spirals appear to be an omnipresent
feature of accretion discs in outburst. Spirals seem to live until decline that
is, for several tens of orbital periods. We then study the formation of spiral
shocks from a theoretical side, using the results of various numerical
simulations. We make a comparison between observations and theory and briefly
discuss the implications of the presence of spirals in the discs of cataclysmic
variables.
