Here's a breakdown:

* Protostar: A protostar is a very young star that is still in the process of forming. It is a dense, hot ball of gas and dust that is still contracting under its own gravity.

* Formation: Protostars form from the collapse of a giant cloud of gas and dust called a nebula. As the cloud collapses, it heats up and rotates faster. Eventually, the core of the cloud becomes so hot and dense that nuclear fusion begins, and a star is born.

* Evolution: Protostars evolve over time, eventually shedding their outer layers of gas and dust to become a main sequence star.

Let me know if you have more questions about stars!