# Difference between quasar and Active Galactic Nuclei?

Are there any differences between quasars and Active Galactic Nuclei (AGN)? As I understand it, they are both caused by extremely luminous electromagnetic emission from material accreting onto a super-massive black hole. If they have the same source, is there still some fundamental difference between them (and if so what is it) or are they two names for the same thing?

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Quasars are sometimes considered a class of AGNs. –  HDE 226868 Aug 11 at 19:40

AGN is a terminology that comes later than quasars. Quasars is the term applied at the beginning, when the first objects of this type have been discovered. They were radio-loud and point-like (the so-called quasi-stellar radio sources). This characterization still holds nowadays. Another property is that quasars are cosmological, that is they are objects in the distant universe (redshift $z > 1$).