In architecture, it is used as a component of vertical traffic between floors. Used for traffic contact between floors and when the height difference is large. Multi-storey and high-rise buildings with elevators and escalators as the main vertical means of transportation should also be equipped with stairs. Although elevators are the main vertical means of transportation in high-rise buildings, stairs should still be reserved for escape in case of fire.

Stairs are composed of continuous steps (also known as ladder running), platforms (rest platforms) and enclosure components. The horizontal projection distance between the lowest and highest steps of stairs is the length of steps, and the total height of steps is the height of steps. During the Warring States period, stairs have been carved in the images of heavy houses on Chinese bronzes. 15 ~16th century Italy liberated the indoor staircase from the traditional closed space and made it a part of the building with various shapes and decorations.

Stairs can be divided into single-run stairs, double-run stairs and multi-run stairs according to the flight. The plane shape of the steps has straight lines, broken lines and curves.