The idea is that the CVV is a basic anti-fraud mechanism for so-called Card Not Present transactions, which is why you are often asked for it when paying over the phone or online.

想法是CVV 是基本反舞弊机制所谓的卡不存在交易，这就是为什么经常要求您为它时通过电话或网上支付的费用。

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Much of that fraud comes from transactions where the card is not physically present, such as telephone or internet sales.

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