An Escalator is a moving staircase that moves people between different floors of a building. They are powered by motors. The steps run on tracks. There is a handrail that moves with the escalator, that you hold onto when riding the escalator. There is also an emergency stop button, which stops the escalator, and a key switch, that restarts the escalator, in the up or down direction.
In 1900, the first commercially-sold escalator, and first step-type escalator was installed by OTIS at the Paris 1900 Exposition Universelle, in Paris, France. The escalator won first prize.
The step type escalator is the common type of escalator today. The steps are usually metal, but very old step type escalators had wooden steps. Step type escalators can also go up/down, flat, and then up/down again. On OTIS Next Step escalators, the escalator steps are mounted on most likely hinged circles, and the track appears to be besides the steps, visible from above the steps. This type of escalator is designed to be safer than other step type escalators.