A star that begins as a large cloud of dust and gas is called a nebula.

Here's a breakdown:

* Nebula: This is the initial stage of a star's life. It's a vast cloud of gas and dust, primarily hydrogen and helium.

* Star Formation: Within the nebula, gravity pulls the gas and dust together, creating a dense core. As the core collapses, the pressure and temperature increase. Eventually, the core becomes hot and dense enough for nuclear fusion to begin, igniting the star.

So, a nebula is like the "seed" from which a star is born.