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Quasars and Seyfert 1 (Sy1) galaxies, their lower-luminosity siblings, (AGN is used to refer to quasars and Sy1 galaxies hereafter) are multi-wavelength emitters, with roughly equal energy output extending from the far-infrared (FIR) through to the X-ray region in all AGN, with extensions to radio and/or high energy gamma-rays in ~ 10%. Technological advances, particularly in the infrared (IR), mm, X-ray and gamma-ray regions, have led to a dramatic increase in multi-wavelength observations of AGN over the past decade or so. This, in turn, has led to fundamental improvements in our understanding of the energy generation mechanisms at work in these powerful objects. This paper reviews the current status of our observational knowledge and the energy generation mechanisms responsible for what we see.