ingularity is referred to a quantity, which approaches infinity as another parameter goes to zero. An example is a black hole, in which a very large mass gets concentrated in so short a distance that gravitational forces become infinite and all matter and energy (including light or electromagnetic energy) cannot escape it. At this level all physical laws break down.
A quasar is a point-like source that is associated with radiatively efficient emission of an active galaxy, which means that its central black hole and is undergoing high rates of mass accretion. They are typically among the most distant objects we can observe and have highest red shifts and thus on the fringes of universe.
