Phase transformations refer to the changes that occur in the physical state of a material, such as from solid to liquid or liquid to gas. These transformations are driven by variations in temperature and pressure, leading to different arrangements of atoms or molecules. Common examples include the melting of ice into water and the boiling of water into steam. During a phase transformation, the properties of a material can change significantly. For instance, the structure of ice is crystalline, while water is a liquid with more freedom of movement. Understanding these transformations is crucial in fields like materials science and engineering, where the behavior of substances under different conditions is essential.