Life cycle of a Star

Life Cycle means the phases from birth of an object or a living being to the death or demise of it.
When we see the luminous objects (Stars) in the sky, some stars will be near that it appears bigger than the others that are farther. Sometimes we think of how the light is given by stars to the earth and the like questions run in our mind. Now, let me explain you how a Star like every object goes through a life cycle.

Life Cycle: A Star passes through some phases. In each phase nuclear reactions takes place between the gas molecules under immense pressure. Different types of gas molecules undergo nuclear reaction as the Star shifts from one phase to other phase. The phases are as follows:

1. Birth of a Star: Stars have their birth in a special region of space called Nebula which is filled with gases and dust. A part of nebula begins to shrink due to the pull of its own gravity. This is where the Star is born. As the temperature grows nuclear reaction begins to take place. This nuclear reaction is nuclear fusion where the lightest gaseous molecules participate in this process. why the hydrogen molecules are fused because these are of less dense and are easily fused. This process is called "main sequence".
2. Red Giant: For fusion of every four hydrogen molecules, a helium gas molecule is formed. There comes a stage where the star starts to run out its hydrogen molecules and enough pressure is not available for the fusion of these helium elements. So, the Star begins to shrink in order to get the required pressure. This stage is called Red Giant. At this stage it appears brighter as some hydrogen molecules in the outer surface undergoes fusion and release light energy. If the star mass is less than that of the Sun then it continues to remain in this stage ceasing all nuclear reactions.
3. Red Dwarf: As the Red Giant contrasts further a Red Dwarf is formed which is a small and cool phase of the star. Since it is small in size it is less visible than its predecessors. In this stage helium burns and produces both carbon and oxygen.
4. White Dwarf: It is composed of both oxygen and carbon. The carbon crushes into neon and magnesium and the oxygen burns into silicon and sulfur. This silicon and sulfur further forms into an iron core which does not undergo any reaction as it wont release any energy. So tremendous pressure is needed to fuse the iron which leads to the collapse of the star. Due to this Supernova is formed.
5. Supernova: It is the death stage of the star where it explodes to form a Neutron star by forcing electrons and protons to produce neutrons. Nuclear stars are very dense which further explode to form a Black Hole.
6. Black Hole: Black hole is the last phase of Star which has infinite gravitational force that even don't allow the light to escape from it.