Science-types will tell you that a material is a solid when its molecules are motionless and lined up in flawless geometric fashion, in perfect little rows and columns, like thousands of tiny soldiers at attention. A liquid, on the other hand, is quite the opposite. Liquid molecules are in a constant state of movement and entirely random in their configuration. Many materials, like water and iron, are common in both liquid and solid states. At any given moment, their state depends on their temperature.
Water molecules are disorderly and mobile only to a point, which is thirty-two degrees Fahrenheit.
The liquid has become a solid. Only when every molecule has taken its place in the lattice and come to a standstill will the temperature continue its decline. One of the most fascinating things about vitreous substances is the conspicuous absence of any freezing point or melting point. As temperature decreases, the free-flowing molecules in molten glass simply move more and more slowly, until they are no longer able to move at all. If, on the other hand, we hold glass at a given temperature for a long enough time, crystallization, to some degree, will take place.