In public transport, a request stop, flag stop, or whistle stop is a stop or station at which buses or trains, respectively, stop only on request; that is, only if there are passengers or freight to be picked up or dropped off. In this way, stops with low passenger counts can be incorporated into a route without introducing unnecessary delay. Vehicles may also save fuel by continuing through a station when there is no need to stop.

A bus stop is a place where buses stop for passengers to get on and off the bus. The construction of bus stops tends to reflect the level of usage, where stops at busy locations may have shelters, seating, and possibly electronic passenger information systems; less busy stops may use a simple pole and flag to mark the location. Bus stops are, in some locations, clustered together into transport hubs allowing interchange between routes from nearby stops and with other public transport modes to maximise convenience.