The matter that holds its own shape is called a solid.

Here's why:

* Solids have a fixed shape and volume. The particles in a solid are tightly packed together and vibrate in place. This strong attraction between particles prevents them from easily changing positions, giving the solid its rigid shape.

* Liquids, on the other hand, take the shape of their container. They have a fixed volume but not a fixed shape.

* Gases have no fixed shape or volume. They expand to fill the entire space they occupy.

Let me know if you have more questions!