<p>All quasars are AGN, but not all AGN are quasars.</p>

<p>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 <a href="http://en.wikipedia.org/wiki/Quasar" rel="nofollow noreferrer">quasi-stellar radio sources</a>). This characterization still holds nowadays. Another property is that quasars are cosmological, that is they are objects in the distant universe (redshift $z &gt; 1$).</p>

<p>AGN is the most general term we can use to refer to active galaxies. AGN include all of them (Seyfert galaxies, Quasars, Blazars, etc.). In the end, it seems that the difference among various types of AGN is due to a <a href="https://astronomy.stackexchange.com/a/2492/1038">mix of angle-of-sight/epoch-of-observation</a>.</p>

CC BY-SA 4.0
2020-08-19T16:11:57.347Z
The nearest quasar has  $z \sim 0.05$.
ProfRob
CC BY-SA 3.0
2014-08-12T07:02:20.033Z
2014-08-12T07:02:20.033Z
2017-04-13T12:59:06.910Z
Py-ser
<p>A quasar is a type of AGN. Its main property is that it's galaxy axis points towards the earth and this way we receive its light and radio signals. That's why they are one of the most energetic AGN. Here you can see a relation of all the AGN types: <a href="http://en.wikipedia.org/wiki/Active_galactic_nucleus#Summary" rel="noreferrer">http://en.wikipedia.org/wiki/Active_galactic_nucleus#Summary</a></p>

CC BY-SA 4.0
2020-08-19T16:11:23.460Z
An AGN where the jet axis points towards the Earth is known as a "Blazar" or a BL Lac object. There is no suggestion that the extreme luminosity of more than a small percentage of quasars is caused by beaming.
ProfRob
CC BY-SA 3.0
2014-08-12T06:32:36.813Z
2014-08-12T06:32:36.813Z
Joan.bdm
<p>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?</p>

CC BY-SA 3.0
2014-08-11T19:40:29.887Z
Quasars are sometimes considered a class of AGNs.
HDE 226868
<quasars>
Difference between quasar and Active Galactic Nuclei?
NeutronStar
# Difference between quasar and Active Galactic Nuclei?

(Asked by: username_0 on 2014-08-11)

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?

**Tags:** quasars

> **Comments:**
> **username_1**: Quasars are sometimes considered a class of AGNs.  

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## 2 answers

### Answer by username_4 on 2014-08-12. Score: 7 | Accepted answer

A quasar is a type of AGN. Its main property is that it's galaxy axis points towards the earth and this way we receive its light and radio signals. That's why they are one of the most energetic AGN. Here you can see a relation of all the AGN types: <http://en.wikipedia.org/wiki/Active_galactic_nucleus#Summary>

> **Comments:**
> **username_3**: An AGN where the jet axis points towards the Earth is known as a "Blazar" or a BL Lac object. There is no suggestion that the extreme luminosity of more than a small percentage of quasars is caused by beaming.  

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### Answer by username_2 on 2014-08-12. Score: 7

All quasars are AGN, but not all AGN are quasars.

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](http://en.wikipedia.org/wiki/Quasar)). This characterization still holds nowadays. Another property is that quasars are cosmological, that is they are objects in the distant universe (redshift $z > 1$).

AGN is the most general term we can use to refer to active galaxies. AGN include all of them (Seyfert galaxies, Quasars, Blazars, etc.). In the end, it seems that the difference among various types of AGN is due to a [mix of angle-of-sight/epoch-of-observation](https://astronomy.stackexchange.com/a/2492/1038).

> **Comments:**
> **username_3**: The nearest quasar has  $z \sim 0.05$.  

---

