Closed User Groups (CUGs) is a feature used to restrict access to content to a select group of users on a published site. This video shows how Closed User Groups can be used with Adobe Experience Manager Assets to restrict access to a specific folder of assets. Support for Closed User Groups with AEM Assets was first introduced in AEM 6.4.
Closed User Group (CUG) with AEM Assets
--->Designed to restrict access to assets on an AEM Publish instance.
--->Grants read access to a set of users/groups.
--->CUG can only be configured at a folder level. CUG cannot be set on individual assets.
--->CUG policies are automatically inherited by any sub-folders and applied assets.
--->CUG policies can be overridden by sub-folders by setting a new CUG policy. This should be used sparingly and is not considered a best practice.