Newel posts provide most of the structural support for handrails. The newel posts are the only pieces of wood attached to both the handrail and the ground or support beam. Thus, the installer places the newel posts vertically at intervals along the handrail, where they hold the handrail system aloft.
The spindles are the the vertical supports that span between the horizontal battens that run parallel to the rail. Spindles can come in a variety of shapes and designs. Indoor spindles in households are generally spun on a lathe to create a unique cylindrical design. Spindles provide secondary support and stability to the handrail.
Each segment of a handrail typically only includes two horizontal battens. The battens span between the newel posts and support the top cap of the handrail. The pair of battens provide structural integrity to the handrail.
The top cap is the portion of the handrail that comes in contact with one's hand. This horizontal piece of wood or metal, generally rounded for comfort when users grasp it, sits atop the highest batten.