When traveling to Europe you want to make sure you have the right cards on you. (and tell your bank where you're going to avoid fraud alert calls!).
We always take bank cards as well as credit cards. This year we found out that European issued cards all have a chip, Americans mostly don't. At least ours haven't. Don't be surprised if they are rejected then.
ATM machines will give you money at an exorbitant fee- up to $12 per transaction. In order to avoid these fees, you may want to find out the corresponding European bank of your US bank.
Some restaurants and most supermarkets -at least in Holland and Germany- also refuse your cards when they are chip less.
Be advised that American Express while highly popular in the US and widely accepted here, is not loved very much in Europe. Only German hotels and gas stations take them as I found out the hard way (because of the exorbitant merchant's fees). You're better off to have a Visa or MasterCard on hand.
There are other security measures in play in Europe if you want to transfer money, as I recently found out. In order to move money from one account to another or just pay a bill online, you need a so-called TAN- generator, an ID card that has a chip in it. While filling in online the addressee's name and account number, this gadget generates a TAN that also has to be included in your transaction. Not that you will have much to do with this.Just a thought why security is of such a high standard here and not in the US?
Europeans, especially Germans are almost paranoid about their privacy. No online information about you if you don't want it.No Google street photos if a neighborhood objects.