Various types of trains are designed for particular purposes. A train can consist of a combination of one or more locomotives and attached railroad cars, or a self-propelled multiple unit, or occasionally a single or articulated powered coach called a railcar.
Special kinds of train running on corresponding purpose-built railways are monorails, high-speed railways, maglev, atmospheric railways, rubber-tired underground, funicular and cog railways.
A train hauled using two locomotives is known as a “double-headed” train. In Canada and the United States it is quite common for a long freight train to be headed by three or more locomotives. A train with a locomotive attached at both ends is described as “top and tailed”, this practice typically being used when there are no reversing facilities available.