Stars are like our Sun, but there are many variations of them. One thing is true, they all begin there life by the spark of nuclear fusion at their cores.
Almost every dot in the night sky that we see are stars. All of those stars exist within our Milky Way Galaxy. Very rarely will a lone star actually exist in the spaces between galaxies, it is the norm for stars to only exist within galaxies.
There are two main groups of stars:
* Population II Stars - old, metal poor stars
* Population I stars - new, metal rich stars
In addition, there are two main endings of a stars life:
* Normal stars - like our Sun - end their life as a Planetary Nebula and White Dwarf
* Large stars end their life in a supernova and end up as a Neutron Star or Black Hole
Lifetime of a normal star:
* Dust cloud forms a Main Sequence star that burns for about 10 billion years
* Star ends Main Sequence life and swells to a Red Giant (about the size of Earth's orbit) and burns for 100 million years
* Star sheds is layers as a Planetary Nebula lasting 100,000 years
* Only the core of the star remains as a White Dwarf