A railway or railroad train is a connected series of vehicles for rail transport that move along a track (permanent way) to transport cargo or passengers from one place to another place. The track usually consists of two, three or four rails, but might also be a monorail or maglev guideway.

Propulsion for the train is provided by a separate locomotive, or from individual motors in self-propelled multiple units. Most modern trains are powered by diesel locomotives or by electricity supplied by overhead wires or additional rails, although historically (from the early 19th century to the mid-20th century) the steam locomotive was the dominant form of locomotive power. Other sources of power (such as horses, rope or wire, gravity, pneumatics, batteries, and gas turbines) are possible.

The word 'train' comes from the Old French trahiner, itself from the Latin trahere 'pull, draw'.

There are various types of trains that 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). Trains can also be hauled by horses, pulled by a cable, or run downhill by gravity.