Referrer-Policy is a security-related HTTP header that controls how much referrer information (the address of the previous web page) is included with requests made from a website. By setting this policy, website owners can determine whether browsers should send the full URL, a reduced version, or no referrer data at all when users navigate between pages or click on links. This helps protect user privacy and can prevent sensitive information from being inadvertently shared with third parties. Common values for Referrer-Policy include no-referrer, origin, and strict-origin-when-cross-origin, each offering different levels of information sharing.