Rail Europe

If there is an app, I wouldn't want it, since Rail Europe tends to over-charge. I use trainline.eu

For more on buying train tickets, see www.seat61.com

Thanks so much!!!

What do you think you will need it for? If you're wanting to check schedules, fares, etc., you need the Swiss Railway site sbb.ch/en as they are the ones who actually run the trains in Switzerland. Rail Europe is a third party ticket seller and they don't show all the trains all the time.

Assuming you are talking about rail travel in Switzerland, since you have posted this in the Switzerland section.

There is no point in purchasing normal Swiss Rail tickets in advance. Normal tickets have no discount for advance purchase and are valid on any train on the date listed. Just buy on the day at the station, either from the machine (faster) or the manned counter.
For some of the less busy trains SBB sells some advance purchase tickets. These are only valid on the one train specified when you buy. These tickets are only available online, and only on the SBB website.

For times, use the SBB website or the SBB app. But, remember all rail lines and routes have at least one train per hour, so you can travel whenever in the day you want.

Understood. Thank you so much. I will use the SBB website and the app.
Appreciate it

Follow-up question about rail travel in Switzerland. I want to travel in one day from Basel to Lauterbrunnen, with a layover in Bern for a few hours. When I check the train fares on the sbb.ch web site, I see that it is cheaper to buy one ticket for the entire route, than to buy 2 tickets for each segment: Basel-Bern and Bern-Lauterbrunnen. If I buy the cheaper ticket for the entire trip, am I allowed to lay over for a few hours along the way at an intermediate stop?

For the Bern layover question:
Yes, if you buy a general ticket that says Basel to Lauterbrunnen, and it goes thru Bern, sure, you can get off, sight-see, and get back on (as long as it is the same day).
I'm not sure how to buy those in advance, but no need to. Just buy in Basel.
I did the exact same thing going from Geneva thru Bern to Lauterbrunnen. I got off in Bern and walked down to Einstein's House, returned, and caught the next train.

Layover in Bern - yes that's true UNLESS you purchase a specially priced (discounted) Saver Fare in which case you must be on the exact train for which it was purchased. Otherwise you can hop off at any stop along the way and get back on a later train as long as you stay on the indicated route.

Yes, because Bern is on the route from Basel to Lauterbrunnen. All trains stop in Bern (change of direction) and in some cases you change trains there. If it was off-route, you would need to get a ticket for the longer (and more expensive) route Basel - XXX - Lauterbrunnen.