Quasars are the most distant and brightest objects in the known universe. The word quasar stands for quasi-stellar radio source. Most Quasars, however, have a very low level of radio activity.
Quasars are very bright objects that are powered by Black Holes at the center
When the light emitted from Quasars was analysed it realised that they have a very large redshift meaning that they are travelling away from us at a very high velocity.
It is thought that the extremely high energy levels are due to Quasars being super-massive black holes with millions of time more mass than our own sun.