Blonde Girl On The Wooden Stairs

Carpeting that runs down the middle of the stairs. Runners may be directly stapled or nailed to the stairs, or may be secured by specialized bar that holds the carpet in place where the tread meets the riser.
• Spandrel
If there is not another flight of stairs immediately underneath, the triangular space underneath the stairs is called a "spandrel". It is frequently used as a closet.