Modern vernacular usage has often extended the term "stained glass" to include domestic leadlight and objets d'art created from lead came and copper foil glasswork such as exemplified in the famous lamps of Louis Comfort Tiffany.

Church of the Redeemer
Fisherville, ON.
"He is Risen"
2007

As a material the term stained glass generally refers to glass that has been coloured by adding metallic salts during its manufacture. The coloured glass is crafted into stained glass windows in which small pieces of glass are arranged to form patterns or pictures, held together (traditionally) by strips of lead and supported by a rigid frame. Painted details and yellow stain are often used to enhance the design. The term stained glass is also applied to windows in which all the colours have been painted onto the glass and then annealed in a furnace.

Stained glass, as an art and a craft, requires the artistic skill to conceive an appropriate workable design, and the engineering skills necessary to assemble the decorative piece, traditionally a window, so that it will fit snugly into the window frame for which it is made and also, especially in the larger windows, is capable of supporting its own weight and surviving the elements. Many large windows have withstood the test of time and remained substantially intact since the late Middle Ages. In Western Europe they constitute the major form of pictorial art to have survived. 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'.