  Stellar magnetic activity is an important factor in the formation and
evolution of exoplanets. Magnetic phenomena like stellar flares, coronal mass
ejections, and high-energy emission affect the exoplanetary atmosphere and its
mass loss over time. One major question is whether the magnetic evolution of
exoplanet host stars is the same as for stars without planets; tidal and
magnetic interactions of a star and its close-in planets may play a role in
this. Stellar magnetic activity also shapes our ability to detect exoplanets
with different methods in the first place, and therefore we need to understand
it properly to derive an accurate estimate of the existing exoplanet
population. Here I review recent theoretical and observational results, as well
as outline some avenues for future progress.
