Although glass was first produced in Syria around 3000BC, it wasn't until the Romans appeared that it started to be used in windows.
For many centuries, glass was a rare commodity, a precious and expensive material used very sparingly, but over time various techniques have been developed to make it more economical.
In the beginning, the silica necessary for glass production was sourced directly from rivers and remained unfiltered. The contaminants present ensured the glass produced contained many imperfections, giving it a distinctive look and appeal.
Beechwood ash and soda lime were also used in the process, adding more colour to the glass, which was usually a shade of green. White glass was extremely rare until the beginning of the 19th century, when more efficient furnaces appeared and consistent materials became available.
There are many different types of glass - the main varieties being plate glass, produced by casting and polishing; crown glass and cylinder glass, both created by a blowing technique.
Crown glass, a thin variety, was exceptionally popular in the 18th century, as it attracted a lower tax, the tax being attributed by weight. However, by the middle of the 19th century, the cylinder method of glass production captured the zeitgeist once more.
The manufacture of flat drawn sheet glass began in the UK in the early 20th century, usurping most other types of glass. From around 1959 onwards, the cheap and imperfection-free float glass became available and soon became a firm favourite. Toughened, and laminated glass have since been produced, and glass continues to evolve and develop, technically and aesthetically.