Stairs, stairways, staircases, or stairwells, are building components that provide users with a means of vertical movement with the distribution of separate and individual vertical steps. In a building setting, a flight of stairs refers to a complete series of steps that connects between two distinct floors. Either as conscious design decisions or as reactions to existing spatial conditions, stairs can take on a variety of organizational types from straight runs to spiral, L-shaped, U-shaped, or circular forms. Each stair step is typically comprised of a horizontal tread and a vertical riser.

Stairs are designed to establish a route or bridge between vertical levels by dividing the distance or height into steps feasible for occupants to travel. Stairs refers to a stairway, staircase, or stairwell while steps refers to the individual vertical distances that make up the stairs. There are many various types of stairs that can be straight, curved, or a set of straight pieces connected at a turn or landing. There are general requirements for a stair’s minimum and maximum tread depth and riser, with a tread being the component of the stair that the occupant steps on and a riser being the vertical component between each tread.