In public transport, a request stop or flag stop describes a stopping point at which trains or buses stop only on an as-need or request basis; that is, only if there are passengers to be picked up or dropped off. In this way, infrequently used stopping points can be served efficiently.
Trains save fuel by continuing through a station when there is no need to stop. There is not a significant saving on time, because trains going through a request stop need to slow down enough to be able to stop if there are passengers waiting.