Several definitions of the glass have been offered depending on the selected application :

• for domestic glass or windows, the glass is a solid, transparent, homogenous and brittle material. It is heat resistant and it can be considered as inert versus almost all the liquids and solids.

glass phenomenological behaviour

schematic arrangment of atomes in a vitreous network.

• for structural aspect, this material has a specific structure. The glass is an amorphous solid. It does not possess a long-range order like the crystalls but has short range order. Glass corresponds to a specific state of the matter called vitreous state.

• for processing aspect, the glass is a solid obtained from quenching a viscous liquid or supercooled liquid.