I'd like to take the train on one part of my trip and then rent a car on another part. I'm interested in only going from one city to another in Europe. A Eurailnet advice is a section devoted entirely to train travel, and provides great tips for planning your trip. With a pass or a ticket you may board the train, but you're not guaranteed a seat, sleeper or couchette. To do that you must purchase a reservation.
Night trains require an advance reservation for a sleeper or couchette.
Day trains require seat reservations for all high-speed trains such as TGV, ICE, AVE, X2000, Eurostar and certain InterCity and EuroCity trains. For most other trains, seat reservations are not required. A seat reservation can be purchased for most long distance trains but not for certain local trains. Reservations are not available for Bulgaria, Greece, Portugal or Romania in the U.S., however they can certainly be made locally. Reservations in Eastern Europe can only be requested to and from major cities, and are subject to confirmation.