Student discounts are less common in France than other countries, but simply because young people under 26 are usually offered reduced rates. Some discounts only apply to residents of E.U. countries, but it's worth carrying ID to prove your age and announcing it when buying tickets. Look out for the Ticket Jeune when using the Métro. It can be used on a Saturday, Sunday, or bank holiday, and provides unlimited travel in zones 1 to 3 for 3.40€ . SNCF also offer discounts for under-26-year-olds traveling on national trains (www.voyages-sncf.com).
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.