A train is a form of rail transport consisting of a series of vehicles that usually runs along a rail track to transport cargo or passengers. Motive power is provided by a separate locomotive or individual motors in self-propelled multiple units. Although historically steam propulsion dominated, the most common modern forms are diesel and electric locomotives, the latter supplied by overhead wires or additional rails. Other energy sources include horses, engine or water-driven rope or wire winch, gravity, pneumatics, batteries, and gas turbines. Train tracks usually consist of two running rails, sometimes supplemented by additional rails such as electric conducting rails and rack rails, with a limited number of monorails and maglev guideways in the mix. The word 'train' comes from the Old French trahiner, from the Latin trahere 'pull, draw'.

The Redstone Acceleration & Innovation Network (TRAIN) is an organization launched by FasterCures in 2004 established to create opportunities for medical research organizations to discuss and overcome research challenges that cut across all diseases. TRAIN brings together nonprofit disease research organizations to share information, as well as promote collaboration and innovation in disease research. Headed by FasterCures, TRAIN asserts that collaboration is crucial for efficient biomedical advancement. Participating researchers discuss successes, failures, and best practices that provide lessons learned and valuable ideas that could be scaled up to amplify productivity.