For my backpacking trip to Europe, I knew I would want to travel a lot locally in between cities of the countries I am going to visit and the cheapest way is to do it by bus, but it does take longer. So, the other option was the train. And the European Union makes it easier and cheaper to move around all of Europe through their collective rail system. You can purchase a pass that will allow you to move within all of the countries for a certain number of determined days, a pass to travel within certain countries only also for a determined number of days or a global pass for consecutive dates, so you purchase it for the total length of your travels within Europe, wether it is a month, two or three.
Prices will range depending on the season you buy, for example for low season, prices are twenty percent less. For many countries, even though you have the pass, you have to reserve your seat and the reservation costs an additional amount aside from the price of the global pass. I believe the maximum cost for a reservation will be about ten euros, but it usually is around four or six. High speed trains and overnight trains with bed will cost a little bit more but definitely cheaper than purchasing a single ticket for travel.
It also saves you the hassle of having to book so many trips, during low season you can reserve a couple of hours or even minutes before your trip but if you already have definitive dates then of course go ahead and reserve in advance. Be aware that if you are over the age of twenty five, you only have the option to purchase a first class ticket.
I advise you to download the Eurail app so you are able to check train schedules and availability on the go but you can also refer to the website through this link. A one month global pass will be around 800 euros, for example, and a one destination ticket will be at least sixty euros for a return trip. So figure out the number of trains you plan to take and calculate wether it is cost effective to purchase the pass. By purchasing the global pass though, you are entitled to many discounts throughout Europe like local buses, metro cards, tram cards and even some hotels and hostels. I recommend it because if you’re planning a long term trip or multi-destination trip, not only will it save you all the hassle of figuring out where to take the train and to purchase ahead of time, you will have a better idea on how much you will actually be spending in transportation and you will have a big cost of your trip already considered with your spending.
Hope this helps, if you have any particular questions please do refer to Eurail website.