We outline the two most plausible unified schemes for radio-loud AGN, one linking the high-luminosity sources (quasars and luminous radio galaxies) and one the low-luminosity sources (BL Lac objects and less luminous radio galaxies). We summarize the evidence for anisotropic emission caused by circumnuclear obscuration and relativistic beaming. We describe the classification and general properties of AGN. This review describes the unification of radio-loud AGN, which include radio galaxies, quasars, and blazars. Understanding the origin and magnitude of radiation anisotropies in AGN allows us to unify different classes of AGN that is, to identify each single, underlying AGN type that gives rise to different classes through different orientations. In radio-loud AGN, bipolar jets emanating from the nucleus emit radio through gamma-ray light that is relativistically beamed along the jet axes. Light from the centers of many AGN is obscured by optically thick circumnuclear matter, particularly at optical and ultraviolet wavelengths. The appearance of active galactic nuclei (AGN) depends so strongly on orientation that our current classification schemes are dominated by random pointing directions instead of more interesting physical properties.
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