Safety Tempered Glass is 4 to 5 times stronger then plate glass and does not break into sharp shards when broken like plate glass. Tempered glass is manufactured through a process of extreme heating in a tempering oven and then goes through a process of rapid cooling making it harder then normal glass and safer. When the tempered glass is broken it shatters into small pieces, this eliminates the danger of sharp edges. Tempered glass is often referred to as safety glass. Pictures below show a tempering oven along with tempered and plate glass when broken.