Stained glass could either be a reference to the material of coloured glass or the art of working with it to enhance it aesthetically or functionally. Stained glass has a thousand-year history, throughout which it has been applied almost exclusively to the windows of churches, cathedrals, chapels, and other similar buildings. Traditionally, stained glass is made in flat panels and used as windows. However, the creations of modern stained glass artists include three-dimensional architecture and sculpture.The term "stained glass" has now been conveniently extended to include domestic decorative objects and even copper foil glasswork. This is exemplified by the famous lamps of Louis Comfort Tiffany.
Chemically, stained glass is glass that has been coloured by adding metallic salts during its manufacture. This is then skillfully crafted into stained glass windows, by arranging small pieces of glass to form patterns or pictures, held together by strips of lead and supported by a solid frame. Various methods are used to enhance the design. The term stained glass is also applied to windows in which the colours have been painted onto the glass surface and then fused onto the glass in a kiln.
Stained glass, as an art and a craft, requires the artistic skill to conceive an appropriate and workable design, and the engineering skill to assemble the piece. A good window must fit snugly into its designated space, must block the entry of natural forces, and, most importantly, must be able to support its own weight! Many large windows of vintage buildings have stood the test of time and remained largely intact for centuries. In this context, the purpose of a stained glass window is not to allow those within a building to see the world outside or even primarily to admit light but rather to control it. For this reason stained glass windows have been described as 'illuminated wall decorations'.
