A tram is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport are called tramways or simply trams/streetcars. Many recently built tramways use the contemporary term light rail. The vehicles are called streetcars or trolleys in North America and trams or tramcars elsewhere. The first two terms are often used interchangeably in the United States, with trolley being the preferred term in the eastern US and streetcar in the western US. Streetcar or tramway are preferred in Canada. In parts of the United States, internally powered buses made to resemble a streetcar are often referred to as "trolleys". To avoid further confusion with trolley buses, the American Public Transportation Association refers to them as "trolley-replica buses". In the United States, the term tram has sometimes been used for rubber-tired trackless trains, which are unrelated to other kinds of trams.