The change of a substance from one physical state to another is called a phase change.

Here are some examples of phase changes:

* Solid to liquid: Melting (e.g., ice melting into water)

* Liquid to solid: Freezing (e.g., water freezing into ice)

* Liquid to gas: Vaporization (e.g., water boiling into steam)

* Gas to liquid: Condensation (e.g., steam condensing into water droplets)

* Solid to gas: Sublimation (e.g., dry ice sublimating into carbon dioxide gas)

* Gas to solid: Deposition (e.g., frost forming on a window)

Phase changes are physical changes, meaning that the chemical composition of the substance remains the same. They are driven by changes in temperature and/or pressure.