The upright member found under the handrail and attached to the tread is called what?

The upright member found under the handrail and attached to the tread is called a baluster. Balusters are vertical posts that provide support for the handrail, as well as safety by preventing falls. They are often spaced evenly to create a visually appealing design while maintaining structural integrity.

Balustrades, which is another term in the options, refer to the entire system of balusters along with the handrail and possibly other elements, but they do not specifically denote the individual upright members. A newel, on the other hand, specifically refers to the larger post that often anchors the top and bottom of a staircase, serving as a strong central support for the handrail. Lastly, a stringer is the structural component that provides support for the treads and risers of the staircase itself, but it does not serve the function of supporting the handrail directly. Understanding these distinctions helps clarify why baluster is the appropriate term in this context.