Rolling stock comprises all the vehicles that move on a railway. It usually includes both powered and unpowered vehicles, for example locomotives, railroad cars, coaches and wagons. However, in some countries (including the United Kingdom), the term is usually used to refer only to non-powered vehicles; specifically excluding locomotives which may be referred to as running stock, traction or motive power. Rolling stock is considered to be a liquid asset,[citation (source) needed] or close to it, since the value of the vehicle can be readily estimated and then shipped to the buyer without much cost or delay.
The term contrasts with fixed stock (infrastructure), which is a collective term for the track, signals, stations, other buildings, electric wires, etc, necessary to operate a railway.