Ballistic glass was patented by William E. Nobbe in 1933.
Ballistic glass is built up of several layers of glass that are laminated into one thick windowpane. The glass layers are held together with thin layers of plastic. When for instance a projectile hits the glass, the energy and pressure is distributed over the entire surface of all the different layers of glass and plastic. The projectile thus decelerates so quickly that the pressure is too low to penetrate the windowpane. Some glass layers may break during the collision – but the layers of laminating plastic hold the glass together.