International Window Cleaning Association: Keeping windows spotless takes more than a paper towel and bottle of cleanser. To promote best practices and safety standards among window-cleaning services, the International Window Cleaning Association offers certification programs, training courses, and other resources.

Stained Glass Association of America: Anyone who has traveled in Europe has probably seen the colorful stained-glass windows of the Gothic cathedrals. And contrary to rumors, the Stained Glass Association of America says their creation is not a lost art. SGAA invites people to view or commission a window from any of its accredited members.

National Glass Association: Glass windows have been around since the Roman Empire. But according to the National Glass Association, no one could see through them until the 16th or 17th century, when the English began producing glass windows over burning coal instead of wood fires.

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