This article is from the Europe FAQ, by Yves Bellefeuille firstname.lastname@example.org with help from Martin Rich M.G.Rich@city.ac.uk.
As a very rough rule of thumb, a rail pass may save you money if you
plan on travelling relatively long distances in a fairly short period of
time. Otherwise, you'll probably be better off buying "point to point"
Non-Europeans may buy a "Eurail pass". This pass can be bought before
leaving or in Europe itself, but a surcharge of 10 % must be paid if
bought in Europe. Europeans may buy an "Interrail pass". Passes are also
available for specific countries and regions: consult the WWW pages of
the train companies of the countries you're planning to visit or see