Guardrail - A railing that guards one from falling - typically 42" high with no opening thru which a 4" sphere might pass

Stair Rail - A guard railing as above that also can serve as a handrail depending on height

Handrail - A rigid material usually metal or wood that serves as a graspable surface to maintain one's balance when going up or down stairs usually 34"-38" off the stair nose line.

Newell Post - A starting on ending vertical support

Pickets or Balusters - Vertical pieces that form the interior of stair or guard rails

Lambs Tongue - The graceful reverse bends and taper of the top rail at ends

Feet or Shoes - Attachment points of railings at bottom