One thing you'll notice as soon as you look at your first timetable: there are a lot of different train types. There are national and international trains, slower and high-speed, with and without supplements.
Note: Faster trains often require a supplemental seat reservation, which is usually not covered by rail passes.
The national trains will often be listed in black or green ink, and will have names like "régional," "InterRegio" "stoptrein," "lokalzug," or the optimistically speedy-sounding "ràpido" and "espresso."
Don't be fooled: these are the slowest trains that make the most stops ("espresso" seems to mean it stops in every town for coffee on the way to the destination) in smaller cities and towns.
International and speedier national trains are usually listed in red ink, are a little nicer, make fewer stops, will have names like "Intercity" or "Eurocity," and will require the payment of a supplement if you buy point-to-point tickets (supplements for these trains are covered by rail passes, although you may still need to purchase a reservation).
And then there are the high-speed trains, such as the Eurostar, TGV, Thalys, AVE, ICE, Cisalpino/CIS, etc., which promise the nicest seats and quickest travel between major cities. These may be listed in blue on the timetable, and they require the payment of supplements (and often seat reservations) in addition to tickets or rail passes.
Next page: Overnight trains