Skimming is a method by which thieves capture the magnetic stripe data from your card and use it to create a new, counterfeit card. These counterfeit cards are then used to process unauthorized transactions against your account. There are two main methods of skimming card information:

A small device that appears to be a part of the machine is placed over the card insertion slot of an ATM, gas pump, or other self-service kiosk. As you slide your card into the ATM, this device “reads” the data on the stripe and either stores it or transmits it to a nearby location. Often times, there is also a small, hidden camera that captures your keystrokes as you input your PIN into the machine.