For Visa and MasterCard credit cards, the CVV is a 3 digit number embossed or imprinted on the reverse side of the card.
Whereas for American Express cards, the CVV is the 4 digit number on the front right-hand side of the card above the card number.
Lastly, for State Bank of India (SBI) Cards, the CVV number is printed at the reverse side of the card.
This is an extra security measure to ensure that you have access or physical possession of the card itself in order to use the CVV code.