How does rail travel work across Europe, and what is Interrail?
Interrail (called Eurail for non-European residents) is a pass giving unlimited travel on participating railways across a large number of European countries for a chosen period. It is a genuinely useful product and it is frequently misunderstood in one important respect.
How passes work:
Global pass covering many countries, or a one-country pass.
Continuous — unlimited travel for a set period — or flexi, giving a number of travel days within a longer window. Flexi suits slower itineraries; continuous suits constant movement.
A travel day typically runs to midnight, and overnight trains have their own rules.
The crucial catch: the pass is not always a ticket. Many trains require a seat reservation paid for separately, and on some services these are compulsory and limited.
Where reservations are compulsory and costly: French high-speed TGV services, Spanish AVE, Italian high-speed, Eurostar, and most overnight sleepers. Reservation fees on these can be substantial, and popular routes sell out — pass holders are allocated a limited quota, which can be exhausted weeks ahead in summer.
Where reservations are not required: most German, Swiss, Austrian, Dutch, Belgian and Czech regional and intercity services, where you can simply board. This is why passes work best for itineraries weighted toward central Europe.
Is a pass worth it? Only if you travel enough. For a small number of long journeys booked far ahead, advance point-to-point tickets are frequently cheaper — European operators discount heavily for early booking, exactly as airlines do. A pass buys flexibility, which is worth paying for if your plans are open and worth little if they are fixed.
Other things worth knowing:
Night trains have returned substantially, and save a hotel night.
Some ferries and private railways offer pass discounts rather than free travel.
Regional day tickets in Germany and elsewhere can beat a pass entirely.
Check individual operator rules before travelling.