A passenger train is a train used to transport people along a railroad line, as opposed to a freight train that carries goods. These trains may consist of unpowered passenger railroad cars hauled by one or more locomotives, or may be self-propelled; self propelled passenger trains are known as multiple units or railcars. Passenger trains stop at stations or depots, where passengers may board and disembark. In most cases, passenger trains operate on a fixed schedule and have priority over freight trains.