In Reply to: I always use one posted by lnt on Saturday, 18. February 2012 at 05:10 Bali Time:
Skimming is done with an electronic reader that reads info from the magnetic strip at the back of the card - same way an ATM does. The raised numbers, as far as I know, have no further purpose except for places that still use the old fashioned carbon 'swiper' gadget.