A structural component that supports the treads and risers. Typically there are two visible stringers and at least one hidden under the treads and risers on a staircase. Those that are visible are typically on either side of the stairs. Stringers alongside are generally routed to receive treads and risers for boxed in stairs. An open staircase or open portion of a staircase may have a visible stringer sitting under the treads and risers. A stringer is a main structural support for most stairways. It is also often a finished, visible trim component which in many cases is painted the same color as the risers and other finish trim.
Carriage is another term used to describe stringers.