1. Document Policy

    A mechanism that allows developers to set certain rules and policies for a given site. The rules can change default browser behaviour, block certain features or set limits on resource usage. Document Policy is useful both for security and performance, and is similar to [Permissions Policy](#feat=permissions-policy).

  2. Feature Policy

    This specification defines a mechanism that allows developers to selectively enable and disable use of various browser features and APIs. Feature Policy is deprecated and has been replaced with [Permissions Policy](#feat=permissions-policy) and [Document Policy](#feat=document-policy).

  3. Permissions Policy

    A security mechanism that allows developers to explicitly enable or disable various powerful browser features for a given site. Similar to [Document Policy](#feat=document-policy).