All stars are formed from protostars.
prorostars don't ALWAYS become stars
Glowing cloud sections that will eventually become stars are protostars. These protostars are clouds of interstellar gas and dust, which gradually collapse causing a hot dense core to form and evolve into a star.
On the contrary, "protostar" is the name of an early stage in the development of a star.
Protostars
Protostars are the beggining of stars
Clouds of gas will collapse, under certain circumstances, due to their own gravity. These will eventually become stars. This process is described in more detail in the Wikipedia article on "Protostars".
Clouds of gas and dust, called nebulas and then form into protostars.
Other stars did the stars. This is true in tabloids as well as in astronomy. The birth of stars is usually preceded by the death of nearby stars. Stars going nova cause compression waves in the interstellar medium, causing pockets of gas to reach critical density. These pockets then collapse in on themselves creating protostars. Protostars contract until they reach critical density, and hydrogen in their cores start to fuse. A star is born.
Protostars was created in 1971.
Protostars has 271 pages.
The ISBN of Protostars is 0-345-02393-5.