During checkout I'm asked for a security number. What is that?

Amex 4 Digit Card Verification Number

For your safety and security, Hyster Sisters Store requires that you enter your card's verification number. The American Express verification number is a 4-digit number printed on the front of your card. It appears after and to the right of your card number.

For your safety and security, Hyster Sisters Store requires that you enter your card's verification number. The verification number is a 3-digit number printed on the back of your card. It appears after and to the right of your card number.