  We collate the results of recent high resolution X-ray spectroscopic
observations of 23 AGN, and use the resulting information to try to provide
answers to some of the main open questions about warm absorbers: where do they
originate, what effect do they have on their host galaxies, and what is their
importance within the energetics and dynamics of the AGN system as a whole? We
find that the warm absorbers of nearby Seyferts and certain QSOs are most
likely to originate in outflows from the dusty torus, and that the kinetic
luminosity of these outflows accounts for well under 1% of the bolometric
luminosities of the AGN. Our analysis supports, however, the view that the
relativistic outflows recently observed in two PG quasars have their origin in
accretion disc winds, although the energetic importance of these outflows is
similar to that of the Seyfert warm absorbers. We find that the observed soft
X-ray absorbing ionisation phases fill less than 10% of the available volume.
Finally, we show that the amount of matter processed through an AGN outflow
system, over the lifetime of the AGN, is probably large enough to have a
significant influence on the evolution of the host galaxy and of the AGN
itself.
