what are the names of the parts of a staircase?
['Step. The step is composed of the tread and riser.', 'Tread. The part of the stairway that is stepped on. ... ', 'Riser. The vertical portion between each tread on the stair. ... ', 'Nosing. ... ', 'Starting step or Bullnose. ... ', 'Stringer, Stringer board or sometimes just String. ... ', 'Winders. ... ', 'Trim.']