Question

How did Black hole formed

Answer 1

See,black holes are formed when the stars collapse under their own gravity.
See,there is one limit called Chandrashekhar limit(it is two to three times the volume of sun).
Now if any star has volume larger than the limit,eventually finishes of its fuel and starts to contract (most of the time).
Now ,a point reaches when its density becomes infinite.This point is called "Singularity". At this point its gravity increases so much that it is able to warp space-time at infinity which causes black holes.
These holes have so much gravity that even light is also not able to escape from it,so it is black.
For more info. you can watch the space-time YouTube channel,black holes series!