Permissions-Policy is a security feature implemented via HTTP headers that allows website owners to control which browser features and APIs can be used in the context of their web pages. By specifying a Permissions-Policy header, developers can enable or restrict access to features such as geolocation, camera, microphone, fullscreen, and more, either for the main site or for embedded content like iframes. This helps enhance privacy, reduce potential attack surfaces, and ensure that only trusted origins can access sensitive browser capabilities.