Quasars - quasi stellar objects -  seem to be point like sources of light that are in fact believed to be very distant, as indicated by the very lard redshifts, which places them among the most distant observable objects. Because they are so distant, but still observable to us, they must be emitting a great deal of radiation, of the order of
W, or about
Suns, as much as a large galaxy - this and their apparently point like size makes their nature very mysterious. What could apparently release this amount of energy from such an apparently compact object is not well understood, but may be a result of a large black hole at the centre of a young galaxy swallowing massive amounts of gas and whole stars - many galaxies are observed to have black holes at their centre, like the Milky Way.