Black hole

Formation of a black hole:—
                the space the massive stars which remains stable for long time is due the production of heat from the nuclear reactions taking place inside star which is also responsible to balance the gravitational attraction.
       However when the stars run out of the hydrogen and other nuclear fuels it will start cooling and the gravitation wins over it and then the  star starts collpsing all it's mass inwards to a central point. This central point gets smaller and denser as all the mass of the star is squashed into a single tiny point.
           But not all stars which have collapsed will transform into a black hole.  In order to become a black hole it must compress below a certain radius called schwarzschild radius. It is given by
             R=2GM/c².
Where, M=Mass of the object
             G=Newton's gravitational constant
       So therefore if any object is compressed to schwarzschild radius then it will continue to collapse until it turns to a singularity. For example to make our  earth collapse we have to compress it to such a tiny point till it reaches schwarzschild radius.

What is a black hole:-
                A black hole is a point in space with a such a strong gravity that not even a light can escape out of it. At the centre of the black hole there is a point where whole mass of the black hole is concentrated called a singularity, a point of zero size and infinite density.
              A black hole is where we can't escape the gravitational pull. Nothing can get a high escape velocity to get away from it.
              From Newton's gravitational law F=GM/r², where mass is directly proportional to gravitational force. Since black hole is so massive in mass the gravitational force or pull will also be tremendous which pulls everything towards it.
         And the black hole has a boundary called a event horizon which is the last part of black hole where light can escape the pull of black holes gravity. Inside event horizon everything even light cones are bent inward so much that it can no longer escape. It moves towards that single point called singularity where everything gets crushed into.
     For example going towards black hole is like going near the Niagara falls which is in canoe. If we however paddle up we can come out but once we get closer to it, we are lost. Also a man caught in quicksand, gets pulled into and eventually gets lost.
          
Hawking radiation:-
          According to quantum mechanical uncertainty principle rotating black hole should create and emit particles known as Hawking radiation. Hawking radiation reduces the mass and energy of black hole and is responsible for evaporation of black hole.