Here's why:

* Composition: Stars are primarily composed of hydrogen and helium, which are both gases.

* Size: Stars can range in size from tiny, faint red dwarfs to enormous supergiants many times larger than our Sun.

* Energy source: The immense pressure and heat within a star cause nuclear fusion reactions, which convert hydrogen into helium and release massive amounts of energy, making them shine brightly.

However, other celestial objects can also be considered huge balls of gas:

* Giant planets: Planets like Jupiter and Saturn are gas giants, composed mostly of hydrogen and helium with a rocky core.

* Nebulae: These are clouds of gas and dust in space, often massive and colorful.

So, while "huge balls of gas" is a general description, stars are the most common and well-known example.