Key takeaways. Credit card security codes are three-digit codes on the back of your card (four-digits on the front if you have an American Express card) used to verify that have the physical card.

Where you can find the security code on your card depends on the card's network. Below, CNBC Select explains how to locate it and how security codes work. How credit card security codes work.

Key takeaways. Credit card security codes are three-digit codes on the back of your card (four-digits on the front if you have an American Express card) used to verify that have the physical card.

It's not safe to have security codes texted to your phone. Luckily, there are other ways to log into your accounts.

Your credit card's security code is a three- or four-digit number that helps protect you against credit card fraud. Learn how to find it and why it's important.

Closely guard your credit card security code unless you are certain that a legitimate business needs it – and only if you initiate a transaction.

Discover what a billing ZIP code is and why it's important for credit card transactions. Learn when it's required and how to find your billing ZIP code.

Security Keys for Apple ID provides a powerful additional layer of security for your iPhone, iPad or Mac. Here's how it works and how to set it up.