The term for changes in matter from solid to liquid is "melting." Melting occurs when a solid gains heat energy, causing its particles to vibrate more vigorously and eventually break free from the fixed positions in a crystalline structure. The temperature at which this phase change occurs is called the melting point, which varies depending on the material. For example, ice melts into water when it reaches 0 degrees Celsius (32 degrees Fahrenheit). Melting is a common physical process observed in various materials and plays a significant role in natural phenomena and industrial applications.