Stars are born.

Eventually, large dense gas balls formed,shrinking under their own gravity and consequently heating up on the inside.At some point, the core of such a ball gets hot enough that nuclear fusion occurs.Hydrogen atoms smash together to form helium,accompanied by a great release of energy,strong enough to counteract the shrinking force of the gravity.When the energy pushing out from the fusion reactions matches the gravity pulling all the gas inwards,an equilibrium occurs.From this a star is born.