train is a connected series of vehicles for rail transport that move along a track (Rail tracks) (permanent way) to transport freight or passengers from one place to another. The track usually consists of two rails (Rail profile), but might also be a monorail or maglev (magnetic levitation train) 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 (Electric locomotive) supplied by overhead wires (Overhead lines) or additional rails (Third rail), 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 (Horse railway), rope or wire (Cable railway), gravity, pneumatics, and gas turbines) are possible.

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