RFC 6454 (The Same-Origin Policy)

RFC 6454 defines the "Same-Origin Policy," a security rule used by web browsers. It ensures that scripts or data from one website cannot access or modify content from another website unless they share the same origin—meaning the same protocol (http/https), domain, and port. This policy prevents malicious websites from retrieving sensitive information from other sites, protecting user data and privacy. Essentially, it restricts cross-site interactions, allowing web pages to operate securely and reliably within their own domains while limiting potential security risks from unrelated sites.