Stained glass
Stained glass is coloured glass, most often assembled into windows or panels with strips of lead, or with copper foil. The term is also used more widely to cover any decorative glass where colour is a main feature, including painted, fused and overlay work. It is also the name for the art of making such glass.
The name originally referred to glass that was coloured by staining, in particular by the silver stain that gives yellow, but it came to mean all coloured glass of this kind. Most medieval coloured glass was coloured in the melt by metal oxides, not by surface staining.
Stained glass is a combination of craft and light: its colour is not on the surface but in the glass, and so it changes constantly with the weather and the time of day.