I'm arriving in Berlin on Sunday and am trying to get a grasp on the most efficient way to buy (and validate) tickets for public transportation (specifically trams). Google searches are giving me mixed information Do the ticket machines at the stations accept American credit cards (chip, but no PIN)? Or am I stuck using a debit card? OR is the BVG app more efficient so that we don't have to hold up a line as we all validate individual tickets getting onto a tram, and if so, can I buy tickets for my whole group (2 adults, 2 children over 6, 1 under 6) using the same account? I'm trying to get a clear understanding for what to expect as we'll be fairly jet lagged upon arrival, and everything always seems more complicated on Day 1. Thank you!

Your American credit card with a chip (no pin necessary) will work in the BVG machines. You might want to get the 24-hour Gruppen ticket (good for all of you) for 29 Euro for the AB region (not heading out into the boonies, which is C region) - - it is indeed good for a full 24 hours, not just till the end of that evening. The machines take cash (including bills) too, and give change.

Thank you, this helps a lot! The 24 hour ticket seems like the best option, based on what we have planned the next day.

Does that just need to be validated on the initial journey?

Yes once you buy it (like upstairs at the S-Bahn tracks in Berlin Hauptbahnhof, or at the S-Bahn station at the airport) there will be a nearby stamping machine. Though you could buy the ticket and then wait till you first board a tram to validate it.