The document discusses magnetic levitation (Maglev) trains. It begins by defining Maglev as using magnetic levitation to suspend, guide, and propel trains using magnets. It then explains the basic principles of levitation, propulsion, and lateral guidance that Maglev trains use to operate at high speeds. The document discusses the two main types of Maglev technologies - electromagnetic suspension and electrodynamic suspension. It covers the merits and demerits of Maglev trains compared to conventional trains and airplanes. Finally, it provides examples of existing and proposed Maglev systems around the world.