It is sometimes said that glass is therefore neither a liquid or solid. It has a distinctly different structure with properties of both liquids and solids. Not everyone agrees with this terminology. Material properties of glasses Usually when people talk about solids and liquids they are referring to macroscopic material properties rather than the arrangement of molecules. After all, glass as a material was known about long before its molecular physics was understood.
Macroscopically materials exhibit a very wide range of behaviours.
Solids, liquids and gases are ideal behaviours characterised by properties such as compressibility, viscosity, elasticity, strength and hardness. Materials do not always behave according to such ideals. For example it is possible to take water from being a liquid to a gas at high pressure without passing through a phase transition so at some stage it must be between an ideal liquid and an ideal gas. Some people say that there is no clear distinction between a solid and a liquid in general. A solid, they claim, should just be defined as a liquid with a very high viscosity.