By:  Dorothy Riggs, CFE It’s important that merchant employees and cardholders possess basic knowledge about card skimmers in order to mitigate financial loss to card issuers and cardholders and to thwart reputational loss to merchants. What is a card skimmer? A skimmer is an electronic device that captures card data.   Card data thieves install the small devices onto or into card terminals at various merchants.   Gas pump terminals and ATMs are among their preferred targets.   Unscrupulous employees at restaurants and the like have also been known to use skimmers to steal card data.