A credit card scam can come in many forms. For example, scammers may use spyware or some other scam to obtain your credit card details. A scammer might steal or trick you into telling them your security code (the three or four digit code on your card) and then make purchases over the internet or the telephone. If they know your PIN, they could get cash advances from an ATM using a ‘cloned’ credit card (where your details have been copied onto the magnetic strip of another card).
Of course, there is also a danger of someone using your credit card if it has been physically lost or stolen.