Laminated glass is a type of safety glass that holdstogether when broken. In the event of breaking, it is held in place by an interlayer, usually of polyvinyl butyral (PVB) between two or more layers of glass. The interlayer keeps the glass layer bonded even when broken and its high strength prevents the glass from breaking into large sharp pieces. Thisproduces a characteristic "Spider Web" crack pattern when the impactis not sufficient to fully penetrate the glass.