Stairs are a structure designed to bridge a large vertical distance by dividing it into smaller vertical distances, called steps. Stairs may be straight, round, or may consist of two or more straight pieces connected at angles.
Types of stairs include staircases (also called stairways), ladders, and escalators. Some alternatives to stairs are elevators (also called lifts), stairlifts, inclined moving walkways, and ramps. A stairwell is a vertical shaft or opening that contains a staircase. A flight (of stairs) is an inclined part of a staircase consisting of steps (and their lateral supports if supports are separate from steps).