Stained glass is a term used to relate to several different styles of glass panel construction. Typically a "Stained Glass" window panel incorporates distinct pieces of colored glass in a pattern or design. The design may be geometric, an example is the famous Frank Lloyd Wright stained glass windows and lamps, or pictoral, such as those commonly seen in churches, or abstract with a mix of styles and patterns.
The components of a stained glass window are the pieces of glass, the binding material around the glass pieces, and depending on design, support assemblies (frames or rebar supports).
The glass pieces vary widely as well... traditional flat clear glass that has been painted, cut and polished beveled pieces, glass that has a pattern rolled into its surface, glass that has been "chipped" by a glue-based manufacturing process (called aptly enough, Glue-Chip), to the common Art Glasses made by manufacturers like Bullseye, Spectrum, Uroboros, Gecko, and countless others. Occasionally you will see other objects incorporated in a window, such as a painting, cut wine bottles, brass filigree, or sculpted lead pieces.
The binding material is typically of two styles: Lead Came, or Foiled. Tiffany is commonly given credit (debated) for making the foil tape process popular, while the lead came version of construction has been around much much longer. Sometimes, a binder of sand/mortar and concrete or epoxy is used with large chunks of colored glass as well.
The support assemblies used for stained glass panels consist of the frame and rebar supports. Generally, a window less than three square feet in area can stand without additional support, as long as it is installed vertically. Any window will generally benefit from a lead or zinc came edge for support, and if a window is to be mounted horizontally (such as in a ceiling) additional support is always recommended. While rebar support is usually seen as straight bars across the glass, the rebar can be bent to follow lead lines and still offer a suitable amount of support.
Antique glass panels are valuable even when broken. The older art glasses often were considered much more brilliant and had more "sparkle" because the manufacturing process included the addition of Arsenic. Also, since it is harder to recycle the colored glasses used in window making, re-cutting and using the pieces of a window that cannot be restored in another piece is a smart alternative to throwing it away.