The stair riser is the vertical plan that "rises" from the tread below to intersect the tread above to form the stair nosing. (See the diagram below.) The riser is the most visible part of stairs when looking up the staircase. The riser receives virtually no contact with the foot; therefore, decorative flooring can be installed on the riser.
For example, in Tampa, many homes have a Mediterranean style with porcelain or terra-cotta tile. Our customer may elect to have us install a decorative blue, mosaic tiles on the riser if we are installing ceramic tile on the stairs.
Example of Stairs with Visible Risers When Looking Up the Staircase.