A transom window, or a small, detail window over a door or atop another window are used for many reasons.
Traditionally they're known for being fan-shaped and the most common use is separating the framing from a door from the framing of a window.
In many cases they can be strictly decorative and in other cases for adding light.
In today's modern design, you're likely to come across ventilating transoms in spa-like bathrooms, adding diffused light and ventilation.
This article first appeared on Houzz.