Solar and stellar activity cycles

A variety of different dynamo models have been proposed for the Sun. While the basic ingredients of the solar dynamo are known, there is no general agreement about the combination and the relative importance of these basic processes. Unfortunately observational constraints are not strong enough to clearly distinguish between different dynamo models. Studying stellar magnetism of the lower main-sequence allows us to impose additional constraints on the fundamental dynamo process and allows to investigate how the properties of dynamos change when rotation and convection zone depth are different from the solar values. We briefly summarize the current state of this field and give an outlook for future improvement including theoretical considerations, new observations and the contributions expected from asteroseismology.