A train is a form of transport consisting of a series of connected vehicles that generally runs along a rail track to transport cargo or passengers. The word "train" comes from the Old French trahiner, derived from the Latin trahere meaning "to pull" or "to draw".

Motive power for a train is provided by a separate locomotive or individual motors in a self-propelled multiple unit. Although historically steam propulsion dominated, the most common types of locomotive are diesel and electric, the latter supplied by overhead wires or additional rails. Trains can also be hauled by horses, pulled by engine or water-driven cable or wire winch, run downhill using gravity, or powered by pneumatics, gas turbines or batteries.