A spindle is typically found in which building component?

A spindle is a vertical post or support that is commonly found within a stair system. It serves as a design element as well as a functional component, typically used in railings and balustrades to provide stability and safety. The presence of spindles is especially notable in residential staircases, where they are spaced between the handrail and the floor to prevent falls and to ensure safety while ascending or descending stairs.

In contrast, spindles are not a characteristic feature of wall systems, ceilings, or roofs. These components may include various structural and finishing elements, but the distinct architectural feature of spindles is unique to stair systems. This structural role, along with the aesthetic appeal they provide, solidifies the connection between spindles and stair systems specifically.