While using your US credit card overseas was once frustrating because of the high fees involved, now those who wish to use their cards across the ocean may face one more problem – card rejection. Most of the rest of the world is fast moving to a chip and PIN system, an entirely different processing system from magnetic strip technology.
As a result, in many places around the world, your US credit card won’t even work with the technology. Chip and PIN cards rely on microchips embedded in cards, something most US cards don’t have. The reason behind this move for many countries is a security issue. Magnetic strip cards are far more prone to fraud than this type of card.
There are few automated machines outside the US that can even accept this type of card, so it could continue to be a problem. Fortunately, Visa has just announced they are going to work on implementing a chip and PIN system in the US soon.
Source: http://blogs.reuters.com/reuters-money/2011/09/28/why-u-s-credit-cards-fail-overseas/

