Public transport (also public transportation or public transit) is a shared passenger transportation service which is available for use by the general public, as distinct from modes such as taxicab, car pooling or hired buses which are not shared by strangers without private arrangement.
Public transport modes include buses, trolleybuses, trams and trains, rapid transit (metro/subways/undergrounds etc) and ferries. Public transport between cities is dominated by airlines, coaches, and intercity rail. High-speed rail networks are being developed in many parts of the world.
Urban public transport may be provided by one or more private transport operators or by a transit authority. Public transport services are usually funded by government subsidies and fares charged to each passenger. Services are normally regulated and possibly subsidized from local or national tax revenue. Fully subsidized, zero-fare (free) services operate in some towns and cities.
For historical and economic reasons, there are differences internationally regarding use and extent of public transport. While countries in Old World tend to have extensive and frequent systems serving their old and dense cities, many cities of the New World have more sprawl and much less comprehensive public transport.
Passenger rail transport is the conveyance of passengers by means of wheeled vehicles specially designed to run on railways. Trains allow high capacity on short or long distance, but require track, signalling, infrastructure and stations to be built and maintained. Urban rail transit consists of trams, light rail, rapid transit, people movers, commuter rail, monorail suspension railways and funiculars.
Commuter, intercity, and high-speed rail
Commuter rail is part of an urban area's public transport; it provides faster services to outer suburbs and neighboring towns and villages. Trains stop at all stations, that are located to serve a smaller suburban or town center. The stations often being combined with shuttle bus or park and ride systems at each station. Frequency may be up to several times per hour, and commuter rail systems may either be part of the national railway, or operated by local transit agencies.
Tram and light rail
Trams are railborne vehicles that run in city streets or dedicated tracks. They have higher capacity than buses, but must follow dedicated infrastructure with rails and wires either above or below the track, limiting their flexibility.
A rapid transit railway system (also called a metro, underground, or subway) operates in an urban area with high capacity and frequency, and grade separation from other traffic.