Page "Stellar evolution" Paragraph 1

Stellar evolution is the process by which a star undergoes a sequence of radical changes during its lifetime.

Depending on the mass of the star, this lifetime ranges from only a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe.

All stars are born from collapsing clouds of gas and dust, often called nebulae or molecular clouds.

Over the course of millions of years, these protostars settle down into a state of equilibrium, becoming what is known as a main sequence star.