  The solar activity cycle is a manifestation of the hydromagnetic dynamo
working inside our star. The detection of activity cycles in solar-like stars
and the study of their properties allow us to put the solar dynamo in
perspective, investigating how dynamo action depends on stellar parameters and
stellar structure. Nevertheless, the lack of spatial resolution and the limited
time extension of stellar data pose limitations to our understanding of stellar
cycles and the possibility to constrain dynamo models. I briefly review some
results obtained from disc-integrated proxies of stellar magnetic fields and
discuss the new opportunities opened by space-borne photometry, made available
by MOST, CoRoT, Kepler, and GAIA, and by new ground-based spectroscopic or
spectropolarimetric observations. Stellar cycles have a significant impact on
the energetic output and circumstellar magnetic fields of late-type active
stars which affects the interaction between stars and their planets. On the
other hand, a close-in massive planet could affect the activity of its host
star. Recent observations provide circumstantial evidence of such an
interaction with possible consequences for stellar activity cycles.
