PCI DSS, or the Payment Card Industry Data Security Standard, is a set of security guidelines and practices designed to protect credit and debit card transactions from data theft and fraud. It outlines requirements for secure processing, storage, and transmission of cardholder information. These standards apply to any organization that handles card payments, aiming to ensure they maintain a secure environment by implementing measures like encryption, access control, and regular security testing. Essentially, PCI DSS helps businesses safeguard sensitive financial information and reduce the risk of security breaches.