An escalator is a moving staircase which carries people between floors of a building. It consists of a motor-driven chain of individually linked steps on a track which cycle on a pair of tracks which keep them horizontal.

Escalators are used around the world in places where lifts would be impractical. Principal areas of usage include department stores, shopping malls, airports, transit systems (railway/railroad stations), convention centers, hotels, arenas, stadiums and public buildings.

Escalators have the capacity to move large numbers of people. They can be placed in the same physical space as a staircase. They have no waiting interval (except during very heavy traffic). They can be used to guide people toward main exits or special exhibits. They may be weatherproofed for outdoor use. A nonfunctional escalator can function as a normal staircase, whereas many other methods of transport become useless when they break down or lose power.

Escalators typically rise at an angle of about 30 degrees from the ground. They move at 0.3–0.6 metres (1–2 ft) per second (like moving walkways) and may traverse vertical distances in excess of 18 metres (60 ft). Most modern escalators have single-piece aluminum or stainless steel steps that move on a system of tracks in a continuous loop.