How does a railway metro work?
The typical railway metro runs an electric powered motor fixed at every wheel of the train, it's motor have two coils inside it, the first one gives high power to start the train and moves it and the second one is for high speeds, the train brakes with special braking pads the same way the car brakes.
"Metro" is a generic name for an urban railway system. Many cities have a Metro. For example: Paris M��tro, Rome Metro, Madrid Metro, Amsterdam Metro, Newcastle Metro, etc., etc. All the comments in the first answer are true, but they are also true of all electric multiple unit trains, from trams to the ICE high speed train I was on earlier today. Typical for a Metro are fixed routes with high frequencies on each route (one train every 2-5 minutes). Not necessarily all wheels have a motor on them.