One of the most important pieces of glass, but often the most overlooked, is the glass in your back windshield. Your rear glass window is also known as a backlite, with lite being the technical glass industry term used to denote a pane of glass.
In addition to its obvious safety purpose, the glass in your rear windshield performs a number of other valuable functions. It helps provide a more open feeling for the inhabitants in the car, it brings more light into the interior of the car, it helps increase visibility for occupants and in times of bad weather, and it adds to the aesthetics of your vehicle.
But the most important thing that your car’s back windshield does involves safety. It helps create the "passenger cocoon" to keep you safe and reduce injuries in the event of an accident.
Most back windshields are curved and also sit in the back windshield frame at an angle. Van and truck sliders are the exception to this rule. The windshield at the back of the truck is usually at a 90° angle. These back windshields, known as truck sliders, often experience a higher degree of breakage than other pieces of back car glass. This is especially true when the slider opens to the outdoors on one side.
Most backlites are made of tempered glass. Tempered glass is glass that has been heated and cooled to increase the strength on the surface of the glass. It takes more force and a higher amount of pressure-per-square-inch to break tempered glass than it does to break annealed glass. While most front windshields are laminated, the glass in most rear car windows is tempered. Thus it will break in a different breaking pattern than your front windshield will.