Annealed Glass — the default glass used by glaziers and window manufacturers when extra safety is not necessary. Laminated Glass — glass produced by bonding two or more pieces of glass with tough polyvinyl butyral interlayers to create one sheet of laminated glass. When laminated glass is broken, the interlayer(s) hold the glass together to provide increased safety and security. Tempered Glass — glass that has gone through a special process to give it superior strength and thermal resistance. Tempered glass is used in situations where safety is a high priority, as it breaks into many small pieces (they look like crushed ice) rather than jagged shards. Tempered glass cannot be cut following the tempering process. Fenestration — from the Latin word “fenestra”, meaning window, fenestration and its derivatives are used to describe items related to the window industry. IGU or IG Unit — industry abbreviation for Insulated Glass Unit. Lite — pane of glass used in a window.