According to Merriam Webster, a transom is: ‘a window above a door or other window’. The experience of a transom is so much more.
On the exterior of a home, it is the window to the sky. Sometimes we include transoms on doors leading to a porch. The additional window space allows more light in.
Inside it helps bring light to interior rooms, to hallways and accessory spaces. Before the advent of central heating and air-conditioning, transoms provided fresh air and internal ventilation.
We also use transom windows as a design element which visually extends the height of a door or window.