trains are much bigger than Métros, go faster, and often have two floors. In addition to suburban RER lines, there are also suburban railway lines leading to the main railway stations. These lines are run by the SNCF—Société Nationale des Chemins de Fer—which also runs the main long-distance trains. Unless you have a carte orange, you will need separate tickets for the RER and SNCF trains outside central Paris.
DOM-TOM: When France gave up its empire after the Second World War, the word colonie was officially banned. What remains of the French empire is now known as les DOMS-TOMS. The letters stand respectively for Départements d'Outre Mer, or overseas counties, and Territoires Outre Mer, or overseas territories. The French départaments or counties include four that are overseas, namely Guadeloupe, Martinique, Guyana, and Réunion. These are considered to be ordinary French counties, even though they are rather a long way from all the others. They are generally shown on the handy little map that you get at the back of French diaries or planners. The TOM are more independent and even farther away and compromise New Caledonia, French Polynesia Wallis-et-Futuna, St. Pierre-et-Miquelon, and the French Southern and Antarctic Lands.