As a material "stained glass" is glass that has been coloured by adding metallic salts during its manufacture, and usually then further decorating it in various ways. 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 enamelled glass in which the colours have been painted onto the glass and then fused to the glass in a kiln; very often this technique is only applied to parts of a window.