That's correct! When a substance changes from a solid to a liquid, it's called melting.

Here's why:

* Solids have a fixed shape and volume because their particles are tightly packed and arranged in a regular pattern.

* Liquids have a fixed volume but take the shape of their container. Their particles are closer together than in gases but have more freedom to move around.

When you add heat to a solid, the particles gain energy and vibrate faster. This increased vibration eventually overcomes the forces holding the particles in their fixed positions, allowing them to move more freely and transition into a liquid state.