Discover how credit card validation codes work and protect against fraud. Learn about their placement, security role, and examples to secure online transactions.

US credit card giants said they will implement a new merchant category code for the nation’s gun retailers, which gun control activists say will help flag potential mass shooters and gun traffickers.

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. You typically ...