All shower glass is tempered, which means that it is four to five times stronger than standard glass, and does not break into sharp points when it does break. If it were to break, it would shatter into small oval shaped pebbles, a safety feature that makes it perfect for showers.
Tempered glass in shower enclosures is made by the same method as oven windows, computer screens, skylights, door windows, and is similar to auto glass, although windshields are made with 2 layers of tempered glass and a sheet of plastic between, so the window tends to hang together when broken.
For shower glass, there are several types of glass, including glass blocks:
Clear glass: Standard clear glass has some iron content, which gives it a slight green hue.
Ultra clear: This type is low in iron, making it ultra clear, there is no tint to the glass at all, giving it a crystal edge.
Rain glass: Patterns of crystal rain give a distinctive decorative look. Admits light, while providing vision control. Only one side of the glass is patterned, leaving the other side smooth for easier cleaning.
Bronze glass: This is a dark-tint option for shower enclosures. The opaque bronze glass reduces what can be seen through it, adding privacy. Very aesthetically pleasing product.
Glass blocks: Are sometimes used, with very nice effects, for shower surrounds. They can be installed as a curved wall or a typical straight wall style.