Young Blonde Girl Undresses Her Lingerie On Stairs

The part of the stairway that is stepped on. It is constructed to the same specifications (thickness) as any other flooring. The tread "depth" is measured from the outer edge of the step to the vertical "riser" between steps. The "width" is measured from one side to the other.
• Riser
The vertical portion between each tread on the stair. This may be missing for an "open" stair effect.