A type of credit card often called a "smart card" or "chip and PIN card" is becoming increasingly common in Europe. These cards are designed with extra layers of security, such as microchips that can be programmed with user information and a four-digit personal identification number, or PIN, that must be entered when making a purchase.

While many European establishments accept U.S. credit cards and smart cards, there are exceptions. "Some European automatic vending machines require consumers to use credit cards with smart chips or PINs," says Susanna Zaraysky, budget travel expert and author of "Travel Happy, Budget Low." Zaraysky learned this when she was in a rush at a train station in France. She tried to purchase her train ticket at a kiosk that only accepted cards with chips. "I had to wait in a long line to buy my ticket," she says.