What is the life cycle of a star?

A star is large ball of gas that gives off light from an ongoing nuclear reaction.The reaction starts when temperatures in the dense gas core reach about 1800,000F and this nuclear fusion can go on for billions of years.Stars about to be born from a cloud of gas and dust are called protostar;bright stars like our sun are in the prime of life.Aging stars expand and grow into hot red giants,then they cool,and shrink into bright white dwarfs.When a star runs out of fuel,it reaches the end of its life,like this doomed star captured by the Hubble Teleschope