Stained glass windows are windows made from colored glass which has been arranged to create an abstract design or pictorial image. They appear widely in much of the Northern Hemisphere, especially in religious architecture. Many people enjoy the aesthetic of stained glass windows, which flood an interior space with multicolored light and serve an ornamental function, and formal buildings sometimes include stained glass accents. The intent behind stained glass windows is not concentrated on the admission of light; it is to enhance a space, tell a story, or awe the observer.

The process to create stained glass windows is quite painstaking, and involves soldering together individual panels of stained glass, sometimes in the hundreds for very large or complex windows. The pieces of stained glass are cut into various shapes and arranged, usually on a large work table, and the artisan must have a good idea for how the window will look and feel when it is complete. The pieces are slowly attached to one another and then enclosed in a larger frame which will hold the window rigidly in place once it has been installed.

Designing for stained glass takes training. Stained glass windows are often viewed from a great distance, so the pattern must be discernible even when the window is very far away. Most stained glass windows use very simplistic, basic patterns with large blocks of color so that the design will read well, although there is much more flexibility with abstract work, where details like faces and flowers need not be conveyed. Extremely complex designs may only read well up close, and more suitable for entryways and other intimate areas.

When well designed and assembled, stained glass windows can last for centuries, and there are numerous examples in Western Europe of medieval stained glass windows in cathedrals and smaller churches. In most cases, these stunning translucent pictures depict saints, stories from the Bible, or well-heeled patrons of the cathedral. When the sun strikes these stained glass windows, they turn into living jewels of light, and transform the interior of a building.

On a smaller scale, stained glass windows are often used as decorative accents in homes and businesses. Private areas which need some natural light may use stained glass windows, while stained glass panels are also used to make ornamental signs, such as labels for restrooms and dining areas. In some instances, a primarily clear window may have stained glass accents such as geometric shapes or flowers to add some visual interest while still allowing plenty of natural light into the space.