Most of the rail networks have a discount card program, normally with versions for youth, adults, seniors and the disabled offering a standard discount on domestic tickets. You may need local documents or residency to obtain it but often all you need is a passport photo and ID. The discounts do vary though, and cards are valid for one year unless otherwise noted.

To save money on a multiple destination trip you may want to look into purchasing Inter Rail passes for Europeans, or Eurail passes for non-EU citizens. The Interrail Pass is less popular in these days of discount airlines and various affordable air passes, but it remains a uniquely flexible way to travel — you can literally arrive at a city, decide you don’t like the look of it, and zoom off on the next train out.

The RailPlus is a program that offers a 25% discount on all border crossing train tickets into Belgium, Bulgaria, Denmark, Finland, Greece, Great Britain, Italy, Croatia, Lithuania, Luxembourg, Netherlands, Austria, Poland, Romania, Switzerland, Slovakia, Slovenia, Serbia, Montenegro, Czech Republic, Ukraine and Hungary. It is included in some national discount cards, although it must be purchased separately in other countries. In France, Ireland, Sweden, Portugal, Spain and Norway the Railplus scheme is only for those under the age of  26 years. The RailPlus card also provides a discount on some international ferries.