Even though glass seems to be a solid material, it is technically a liquid material. The general characteristics of the viscosity of liquids also apply to the characteristics of glass.
From the excessive chilled alkali and earth alkali metal oxides together with the solvent of various other metal oxides forms a main liquid product (SiO2) sillicium. It is known that by protecting its amorphous structure, it inorganically forms a solid state. During production, the quick cool down period causes the crystal structure to be an amorphous structure. This structure gives the glass durability and transparency features.
In other words glass is a flowing material. The flow of the liquid happens is such little time that it cannot by observed by the human eye. This is why we know of glass of a solid state.
