You will find a lot information on this page:
http://www.seat61.com/Railpass-and-Eurail-pass-guide.htm almost 6 years ago
Eurail passes are designed for travel within Europe, not to Europe. Depending on where you're coming from, you will likely want to fly to Europe first and then use the Eurail.
Depending on how long you are traveling and which countries you are going to, a Eurail pass might not be the best investment for you. We just did two months in Eastern EUrope and only used a train three or four times. They often require advance bookings and are more expensive. Buses run frequently and are often cheaper. almost 6 years ago