Toughened glass, also known as tempered glass, is a type of safety glass that is up to four times stronger than annealed glass. It is made by heating the glass to a high temperature and then rapidly cooling it, which creates internal stresses that give the glass its strength. Toughened glass is widely used in applications where safety is a concern, such as automobile windows, shower doors, and glass partitions. When toughened glass breaks, it shatters into small, rounded pieces rather than sharp shards, reducing the risk of injury.