By Rick Steves
It's wise to carefully compare passes to find the best fit for your itinerary and style of travel. The range of options may seem intimidating, but mostly it's a matter of simply knowing which countries you intend to travel in and for how many days.
First find the pass that best matches the area you'll be traveling in. If you're planning on covering a lot of ground by train, you probably want a Global Pass, which gives you Europe by the tail, buying you unlimited travel on public railways in most of Europe. Even if you're traveling by train in just two countries, the Global Pass is likely your best option, as it generally makes little sense to cobble together several single-country passes.
A few multicountry regional passes, available for Scandinavia and parts of eastern Europe, can be cheaper if one of them happens to fit your plans.
Virtually every European country has its own single-country pass. The relative value of a single-country pass over individual tickets really varies across Europe, so it pays to price it out before buying one. Factor in convenience as well, as passes save some hassle in countries where seat reservations usually aren't required, and the unique bonuses offered by certain passes, such as Switzerland's (which covers more than just trains) and Germany's (which also covers a few international routes).
While not all passes offer a non-flexipass option, understanding how a flexipass works is key to being a savvy pass shopper.
A flexipass lets you pay only for the days on which you actually travel. You don't have to decide beforehand which days you'll travel on, but you do have a certain window in which you must use up your train days (for most passes, that's either one or two months after you start using the pass). You can take as many trips as you like within each travel day, which runs from midnight to midnight (though most direct overnight rides can count as only one travel day).
A few passes are also available as a continuous pass, which can save you money if you plan to travel nearly daily and cover a lot of ground (whereas a flexipass is likely better if you plan to linger for a few days at most of your destinations). Global, BritRail, German, and Swiss passes offer this option. If you have a 15-day continuous pass, you can ride the trains as many times as you like for 15 days. The number of days you can travel with a one-month continuous pass depends on the month you start traveling: If you set off on any day in February, the pass is only good for the next 28 days; if you start in July, it's good for 31 days.
For those with open-ended plans, continuous passes can provide an extra sense of flexibility. Let's say you're planning a three-week trip and choosing between two versions of a Global Pass: a three-week continuous pass and a cheaper 10-days-in-two-months flexipass. For not much more money, the continuous pass gives you the freedom to take any train without wondering if a particular trip justifies the use of a travel day.