A blackhole is the result of mass becoming so dense that the gravity crushes it into something incredibly tiny or perhaps even into a singularity. But BHs can grow by colliding with other masses. The center of most, if not all, galaxies has SMBHs (Super Massive Black Holes).What is difference between a Black hole and a Quasar ?
Quasars are visible in the electromagnetic spectrum. Black holes are not.What is difference between a Black hole and a Quasar ?