Many stars across all classes possess strong enough magnetic fields to
influence dynamical flow of material off the stellar surface. For the case of
massive stars (O and B types), about 10\% of them harbour strong, globally
ordered (mostly dipolar) magnetic fields. The trapping and channeling of their
stellar winds in closed magnetic loops leads to {\it magnetically confined wind
shocks} (MCWS), with pre-shock flow speeds that are some fraction of the wind
terminal speed that can be a few thousand km s−1. These shocks generate
hot plasma, a source of X-rays. In the last decade, several developments took
place, notably the determination of the hot plasma properties for a large
sample of objects using \xmm\ and \ch, as well as fully self-consistent MHD
modelling and the identification of shock retreat effects in weak winds. In
addition, these objects are often sources of Hα emission which is
controlled by either sufficiently high mass loss rate or centrifugal breakout.
Here we review the theoretical aspects of such magnetic massive star wind
dynamics.Comment: Accepted for publication invited chapter of the Handbook of X-ray and
Gamma-ray Astrophysics published by Nature Springer. arXiv admin note: text
overlap with arXiv:1509.06482, arXiv:1605.0497