A Nebula is a huge cloud of dust and gas in the space, which contains atoms of hydrogen, nitrogen, oxygen, carbon, graphite, water and many other elements to form stars and planets.
When a dense region of a nebula collapses under its own gravity, a protostar is generated. Nuclear fusion begins inside the protostar once it gets hot enough. As it starts to shine, a new star is born! When a star runs out of fuel, it will die by expanding hugely, and becoming cooler and redder. But the life expectancy of a star is way longer than human, which can last billions of years.
Helix Nebula