1.

The beginning of 3 is Japanese JCB and AMERICANEXPRESS.

2.

The beginning of 4 is the international brand VISA credit card (the world's first credit card organization)

3.

Start with the international brand MasterCard.

4.

The beginning of 6 is China UnionPay single currency card (or American discover).

CVV code:

The security code of VISA card is called CVV2 (card verification value 2), which has 3 digits and is printed on the last 4 digits of the card number on the back of the credit card.

MarsterCard's security code is called CVC2 (Card Verification Code 2), which has 3 digits and is printed on the last 4 digits of the card number on the back of the credit card.

The security code of Discover card is called Cardmember ID, which has 3 digits and is printed on the signature column on the back of the credit card.

The security code of American Express is called CID (Card Identification Number), which has 4 digits and is printed on the front of the credit card above the credit card number.

The security code of JCB card (Japan Credit Bureau) is called CAV2 (card authentication value 2), which has 3 digits and is printed on the back of the credit card number.

CVV is the card verification value, and MasterCard is called the card verification code (CVC). VISA CVV and MC CVC are 3-digit or 4-digit numbers generated by card number, expiration date and service constraint code, which are generally written in the 2-track custom data area of card magnetic stripe.

Technical principle:

1.

The "visa authentication" service is based on a technical platform called "3D security". The specification and communication protocol of this technology are encrypted by SSL technology, and now most online businesses adopt SSL technology.

2.

The "Visa Verification" service logo will be displayed on the web pages of online merchants participating in the service, and it will also appear every time the cardholder registers online shopping and enters his personal password for verification.

3.

The function of visa verification is not only to verify the legality of overseas websites, but also to verify the identity of cardholders and reduce the risk of overseas online shopping being stolen.