This architectural drawing is Stair structure with detailing. There are three main components in a typical staircase: stringers, treads and risers. The riser is the vertical surface of the stair. The tread on the other hand is the horizontal surface of the stair and the part of the stair you step on. Nosing is the portion of the tread that overhangs the front of the riser. For more details and information download the drawing file.