Death of Star
We know that star is made up of hydrogen gas. This hydrogen atom fuses together to form helium atom and release large amount of radiation When force of radiation balances force due to gravity star remains star. This force of radiation balance gravity till star start fusing iron. Fusion of iron do not provide sufficient force to balance force due to gravity as a result start get collapse into it’s own gravity. Now according to Chandrasekhar limit One of three :- White dwarf, Neutron star or Black hole will be form.
Birth of Black Hole
A super massive star (at least 3 times mass of our sun) when die forms Neutron star or Blackhole. If mass is lass than required mass than it will form white dwarf. If star is massive enough to trap light it form Black hole or it become Dense Neutron star. This limit was given by Indian scientist Subrahmanyam Chandrasekhar and thus it is known as Chandrasekhar limit.
Death of Black Hole
According to Quantum field theory, our universe is made up of different fields. Vibration in these fields produces what we called particles. For eg :- Vibration in Higgs field create Higgs boson (ie, God particles), Vibration in electro magnetic field create Photons. Same way vibration in quantum field produces particle and anti particle for infinitely small amount of time lets say it dt. When these phenomena occur near event horizon anti particle take mass of particle and starts it journey traveling away from event horizon. Thus mass and energy of Black hole reduced. This is very slow process. This process is known as Hawking radiation.