History of glass
Naturally occurring glass, such as obsidian, has been used since the stone age. The first documented glass making is in Egypt around 2000 BC. Glass was first used as a glaze for pottery and other items. In the first century BC the technique of blowing glass was developed and what had once been an extremely rare and valuable item became much more common. During the Roman Empire many forms of glass were created, mostly used in vases and bottles.
The centre for glass making from the 14th century was Venice, which developed many new techniques and became the center of a lucrative export trade in dinnerware, mirrors, and other luxury items. Eventually, some of the Venetian glass workers moved to other areas of northern Europe, and glass making spread with them.