  Active Galactic Nuclei (AGN) are sources of high-energy gamma-rays and are
considered to be promising candidates to be sources of high-energy cosmic rays
and neutrinos as well. We present and discuss various models for ion
acceleration and their interactions with matter and radiation leading to
high-energy neutrino production. We consider neutrino production mechanisms in
both jet-loud and jet-quiet AGN, focusing on disks and coronae in the vicinity
of the central black hole, jet regions, and magnetized environments surrounding
the AGN. The IceCube Collaboration has reported high-energy neutrino events
that may come from both the jet-loud AGN TXS 0506+056 and the jet-quiet AGN NGC
1068. We discuss the implications of these observations themselves as well as
the the origins of the all-sky neutrino intensity.
