Active Galactic Nuclei (AGN) are not longer considered part of a small and 
exotic source population but are now widely accepted to play a significant 
role in the evolution of galaxies through cosmic time.  However, even fifteen 
years after the realization of the close link between the super massive 
black hole mass and the properties of the hosting galaxy many details of 
the interconnection remain unresolved. 
Two complementary approaches are followed to deepen our understanding; 
detailed studies of individual nearby AGN provide detailed insight into 
the physics that trigger AGN activity and link it to the spatially resolved 
host properties, while the large samples of AGN collected from surveys access 
the population properties and their impact on the evolution of their hosts 
with redshift and environment. 
In my talk I will focus on results from recent and ongoing AGN surveys on few 
square degrees (e.g., COSMOS, Stripe82) and introduce the challenges that the 
next generation of wide-angle and all-sky sky AGN surveys (e.g., SRG/eROSITA, 
EUCLID, LSST, ASKAP/EMU)  will encounter. Particular emphasize will be given 
to the technical challenges posed to  the associated multi-wavelength 
identification and characterization programs.