Why does it matter which website you use? Each country has its own national train operator and there are various private operators as well. Almost all these operators offer cheap budget-airline-style fares if you book ahead, but you can only buy these cheap fares at the operator's own website or from an agency directly linked to that specific operator's ticketing system.

For example, let's take Prague to Budapest. My site correctly tells you to use the Czech Railways (CD's) website for this route as it sells cheap advance-purchase tickets from just €19, all international credit cards accepted, no booking fee, and you simply print your own ticket. You even get to choose an exact seat from a seating plan! The cheapest €19 rate is usually available as little as a week ahead, and even the day before you'll usually find fares for €30 or so.

No other website or agency connects to CD's system, therefore no other site can sell CD's cheap fares. However, various high-profile rail ticketing agencies will sell you a Prague-Budapest ticket for a whopping €90 or more via their connection to the French ticketing system through an almost-obsolete inter-operator system called TCV, a conventional ticket which has to be posted to you at extra cost making it over €100, ouch! And your seat is allocated with little or no choice. Can you now see why it matters where you buy?

Ticket delivery matters, too. For example, you can buy a cheap Vienna to Venice ticket at Trenitalia.com, but it 's no good if you're starting in Austria as tickets have to be collected from a Trenitalia self-service machine in Italy! The Austrian Railways website offers print-at-home e-tickets in either direction for this route, so this is the website I recommend for booking this journey in this (or indeed the other) direction.

I take all this into account to tell you the cheapest & easiest way to book each specific journey, whether you live in the UK, USA, Australia, Singapore, wherever.