What fees do credit cards charge for transactions done abroad?

I don't know about fees, but the value of the currency varies based on the dollar. For instance, the British pound is sometimes $1.63, other times like $1.85. It can change daily during your visit. Like when you are home, the store/restaurant may post the purchase on a different day than when you were there, and the credit company will charge you that rate. It is disconcerting to get home and notice the difference, which is usually higher. Check with your card to see if there is a conversion charge, also. I take money orders written in that country's currency, which can be bought from AAA.