Credit Cards have a number of visible anti fraud features such as -
- The number
- Your full name
- Expiry date, and
- The CVV number
It's normally impossible to buy anything online or over the telephone without giving all 4 bits of information. This is why the CVV number is so important and if protected it's hard to steal any money.
Sometimes, you might pay for something and your Card is taken out of your eyesight. The card is then cloned via a special machine. However a cloned card is not as valuable as one with the CVV.
To combat this threat either never let the Card out of your sight or better cover the CVV number up with a small piece of masking tape. Then, if it's been tampered with you'll soon know about it and can cancel the Card.
This fraud is common abroad
Personally I don't use this trick when I'm at home in the UK. But if going away on holiday I always cover up the CVV number on all my plastic as many countries don't as yet use the Chip & Pin system.