This document provides information about stairs, including definitions of key stair parts and types of stairs. It defines a stair as a set of steps leading from one level to another inside a building. The main parts of a stair are identified as the step, tread, riser, handrail, baluster, newel post, run, and nosing. Six common types of stairs are described: straight stairs, doglegged stairs, quarter turn stairs, open newel stairs, three quarter turn stairs, and bifurcated stairs. Spiral or circular stairs are also introduced as a type that is useful when space is limited.