The Life Cycle of a Star
Stars have a life cycle. After they pass from the T Taurus formation period, the enter the main sequence.
Image Source: http://en.wikipedia.org/wiki/File:TTauriStarDrawing.jpg
The proto star enters the main sequence cycle.
The main sequence as shown by the image above is a band of stars that is continuous and distinctive. On the Hertzsprung-Russell diagram it appears on plots of stellar color versus brightness.
After a star has formed, it continues to operate at a high energy level through the use of nuclear fusion where hydrogen atoms fuse into helium. During this stage of the star's lifetime, it is located along the main sequence primarily by its mass.
One of the main characteristics of main sequence stars is that they are in hydrostatic equilibrium where outward thermal pressure (heat from the hot core) is balanced by by gravitational pressure accumulating from the outer gaseous layers of the star.
Once a star begins its fusion reactions, the star may live for millions of years. It can take different directions depending on the amount of initial mass when it became a star.
Star Life Cycle: www.ir.isas.jaxa.jp/ASTRO-F/Outreach/seika_e.html
So, depending on its mass, a star could evolve into a Red Giant then either a SuperNova (explode), collapse into a black hole or dissipate into a nebula.