The first quasars discovered were radio objects which were pointlike in visible light, but their structure could be resolved with radio telescopes. Then it became possible to resolve them in visible light, also; many radio-quiet ones were found as well; so many that most known now are radio-quiet. They are typically a few seconds of arc in apparent size. Using their red-shift determined distances, their physical extent comes out to be a light year or less. They also vary somewhat in brightness, with a period of several months, which also implies a size of few light-months or less, less than the distance to our nearest neighboring star. But we can see each one from its enormous distance: so it is extraordinarily bright. It is much tinier than our galaxy, but also much brighter than our galaxy. What is powering it? That is the biggest quasar question.