Strength, hardness, Flexibility all mean different things when engineers talk about them.
Glass is a brittle material which means it will not deform (change dimensions i.e. stretch) when you apply an external force. The opposite of brittle is a ductile material, like steel, which yields and begins to deform once you apply a load above the material's yield threshold. Depending on the material's application ductility/brittleness can be a desired property.
Strength, hardness, Flexibility all mean different things when engineers talk about them.
Glass is a brittle material which means it will not deform (change dimensions i.e. stretch) when you apply an external force. The opposite of brittle is a ductile material, like steel, which yields and begins to deform once you apply a load above the material's yield threshold. Depending on the material's application ductility/brittleness can be a desired property.