Ever got a charge on your credit card that you never asked for?
It happens to almost everyone sooner or later, and most of us have at least heard of most of the common reasons, but there are several newer wrinkles or sudden resurgences of old tricks that you may not know.
Cross-selling or how you unknowingly "opted in" to buy/subscribe when you left a site after a purchase
Force-posting or how charges can appear on a card you haven't even activated yet.
You can contest either of these with good success, if you notice, and know about the possibility. Otherwise they often try to convince you that it must have been your mistake somehow.
Visa and Mastercard rules state that card data should not be stored, and the CVV, the verification codes are NEVER to be stored.
Usually I make purchases on-line using my card and a bit of software called Shopsafe which produces one-time cards with a specified expiration date and a specified credit limit.