Star

A star (or "sun") is a massive energy-producing sphere of plasma and gas located in space. The region around a star that is held by its gravity, including any planets, moons, comets, and asteroids, is called a planetary system.

Life cycle
A star is formed by a nebula that collapses under its own gravity, the gas of the old nebula forms now a young new born star. Some very weak stars have a lifetime of trillions of years, stars like our sun have a lifetime of several billion years, stars stronger than our sun have a life that is below the billion (some stars life even shorter than 10,000 years!). When stars die most of them becomes slowly dying white dwarfs and end after a very long time cold and dead black dwarfs, the stronger stars dies with a supernova and and up as a neutronstar, quarkstar, preonstar or a black hole.