The direction of movement (up or down) can be permanently the same, or be controlled by personnel according to the time of day, or automatically be controlled by whoever arrives first, someone at the bottom or at the top (of course the system is programmed such that the direction is not reversed while somebody is on the escalator). In the last two cases there has to be an alternative nearby.
Charles Seeberger developed the escalator and installed the first one as an amusement ride at Coney Island, New York in 1897. He joined the Otis Elevator Company and they produced the first commercial escalator which won a first prize at the Paris 1900 Exposition Universelle in France.
Escalators in the London Underground used to have wooden steps, but this was changed after the Kings Cross fire at Kings Cross St Pancras tube station in 1987. Escalators now have metal steps in a continuous loop that move on tracks. Escalators are typically used in pairs with one going up and the other going down. Some modern escalators in stores and shopping malls have glass sides which allow their workings to be viewed. Although most escalators are straight, some shopping malls use curved versions.
When using escalators, passengers who wish to stand and let themselves be carried up or down should stand on one side to allow more impatient users to walk past them. There has been reports of people actually falling off an moving escalator or part of their shoe gets stuck in part of the escalator. However, which side varies from place to place. On the London Underground and Washington Metro, standees are asked to keep to the right.