What does the red spectrum tell us about quasars?

And why is it so frequently linked with quasars?

Quasars are brilliantly shining heavenly bodies that are extremely far away.

In answering the question What does the red spectrum tell us about quasars? ...

Quasars originally meant quasi stellar object, which means things that look a bit like stars.

Well, this implied enormous distances to quasars, which then implied that the, their internal luminosities are huge.

I mean from here, with a telescope and you'll see things that look like stars, they're called quasars.

The super massive black hole paradigm for active galactic nuclei quasars and such is now very well established.

.. and I think that confidently and concisely answers the question, What does the red spectrum tell us about quasars?

But it took really combination of optical and radio astronomy with identification of quasars to really drive his point home.

Those are luminous quasars and even some real galaxies, and so we know that at least some little pockets of the universe have achieved the density contrast which are not the part in a million, but a million for orders of magnitude, in the time elapsed from the microbackground release until then is of the order of half a billion years, so this is not an easy thing to achieve.