On the two main classes of Active Galactic Nuclei
  Active Galactic Nuclei (AGN) are traditionally divided empirically into two
main classes: "radio-loud" and "radio-quiet" sources. These labels, which are
more than fifty years old, are obsolete, misleading, and wrong. I argue that
AGN should be classified based on a fundamentally physical rather than just an
observational difference, namely the presence (or lack) of strong relativistic
jets, and that we should use the terms "jetted" and "non-jetted" AGN instead.
