The term for a physical change that alters the state of a substance is called a phase change. Phase changes include transformations such as melting, freezing, condensation, and evaporation. During these changes, the substance may alter its physical state (solid, liquid, or gas) without altering its chemical composition. For example, when ice melts, it changes from solid to liquid but remains as water. Phase changes occur in response to changes in temperature and pressure and are essential for various natural and industrial processes.