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

Designed as a high-tech marketing resource, QR (quick response) codes have many useful applications. These (usually) black-and-white algorithmic codes are gateways to a potential multimedia nirvana.

Secret codes are all around us, making it easier to communicate information quickly to the people who are looking for it. CB Radio codes, for example, aren’t exactly mysterious—if you’re old enough, ...