Taking it's light and placing it on the light spectrum. The more red shift the farther back in time and farther away the galaxy is. This helps us get closer to what the universe looked like at the time just after the big bang. It also helps us study galaxy formation. So stars need to have a dynamic life cycle.
Stars form when hydrogen atoms in space are pulled together in bigger and bigger spheres.
The reactions on the sun are like atomic bomb going off on Earth. Except the atomic bomb would be like a balloon popping compared to the entire Earth exploding. The release of this energy does two things. A lot of it provides an outward explosive pressure to counterbalance the inward pressure of gravity in the emerging star. This allows the star to remain stable for billions of years.