An amorphous solid, also known as a glass, does not have a true melting point in the same way that crystalline solids do. Instead, it undergoes a process called glass transition when heated. Below the glass transition temperature, an amorphous solid behaves like a rigid solid, while above this temperature, it flows like a liquid. However, unlike the sharp melting point of a crystalline solid, the glass transition is a gradual process over a range of temperatures, and the material becomes increasingly viscous as it is heated. The glass transition temperature is an important property for amorphous solids and is used to characterize their thermal behavior.