The process of changing from a solid to a liquid is called melting.

Here's what happens:

* Heat Energy: When heat energy is added to a solid, the molecules within the solid start to vibrate faster.

* Breaking Bonds: The increased vibrations weaken the bonds holding the molecules in a fixed, rigid structure.

* Movement: As the bonds weaken, the molecules gain enough freedom to move past each other, allowing the solid to lose its definite shape and take the shape of its container.

Here are some examples of melting:

* Ice melting into water

* Butter softening at room temperature

* Chocolate melting in your hand

Let me know if you'd like to know more about the physical states of matter or the process of melting!