  The recurrent activity of radio AGN, with phases of activity alternating with
periods of quiescence, has been known since the early studies of these objects.
The full relevance of this cycle is emphasised by the requirement, from the AGN
feedback scenario, of a recurrent impact of the energy released by the SMBH
during the lifetime of the host galaxy: only in this way can AGN feedback
influence galaxy evolution. Radio AGN in different evolutionary phases can be
identified by their properties, like morphology and spectral indices.
Dying/remnant and restarted sources have been the most elusive to select and
characterise, but they are crucial to quantify the full life cycle. Thanks to
the availability of new, large radio surveys (particularly at low frequencies),
it is finally possible to make a more complete census of these rare sources and
start building larger samples. This paper gives an overview of the recent work
conducted using a variety of radio telescopes and surveys, highlighting some of
the new results characterising the properties of dying/remnant and restarted
radio sources and what has been learned about the life cycle of radio AGN. The
comparison with the predictions from numerical simulations is also discussed.
The results so far show that remnant and restarted radio AGN have a variety of
properties which make these objects more complex than previously thought.
