Trains are a convenient mode of short, medium and long distance travel across Europe. Western and Central Europe has a dense and widely used railway network spanning the entire continent.

source: wikitravel.org

For short distances, European trains are fast, reliable and frequent. For longer distances they can be preferable to flying for several reasons. Trains have more spacious and comfortable interiors, may offer scenic routes, and do not require long waits at security like at airports. They usually run more frequently as well, and take their travellers to railway stations located in or very close to city centres, whereas airports, especially the ones that budget airliners fly into, can be up to 100 km away from the city centre, requiring expensive and time-consuming connecting services. Ultimately, many people may choose the train over the plane for the feeling of romantic travel they provide.

The quality, speed and price of train travel depends on the country, Western European countries generally offering higher speed and more luxurious trains at higher prices than Eastern European countries. When bought on the spot, trains tickets can be more expensive than cheap flights over the same distance, but this difference may disappear when the tickets are booked in advance. Not to forget the costs to get to the airport. Train travel is getting faster every year through the construction of new high speed lines which travel up to 300km/h (190 mph), and upgrading of conventional lines to 200 km/h (125 mph). Especially Germany, France, Belgium and Italy have extensive high-speed networks.

The cost of rail travel varies greatly by country. Eastern European countries tend to offer very cheap travel. Italy is comparatively cheap as well. The most expensive country is the United Kingdom.

If you can, try booking in advance rather than walking up to the ticket desk on the day of travel. Train fares booked in advance are usually competitive with airlines fare, or cheaper. E.g., return tickets from Edinburgh to London are just £25 if booked in advance, a 75% discount on the walk-up fare of £94. German return tickets are 25% cheaper if booked 3 days in advance, 50% if you stay on your destination over a Saturday night, and up to 5 fellow travellers get another 50% off on top of the advance ticket fare. Three people travelling Cologne-Munich and back could thus pay €224 rather than €672 for their entire trip.

Advance booking can be done from home if you want to, through the websites of the national railway companies. For international tickets use the railway website of either country you are travelling through. Compare the fares, as they may differ. Tickets can sometimes be printed at home, they may be mailed to you or made available for collection at a railway station. You will usually be offered the option to reserve seats or sleepers; seats may be free or cost €2; sleepers are usually €20. Reserved seats are recommended especially on long trips.

SOURCE: wikitravel.org