An extranet is a space which is protected by the Space Privacy - Extranet for Confluence app. To create a new extranet space, click "Create Space" in the dashboard or click on "Spaces" and select "Create Space". In the following dialog, select extranet space and click next.
You can then choose a name for the extranet space, enter a space key, and optionally add users or groups to be extranet space managers and extranet user managers. Click create to create your new extranet space. When an extranet space is created, the app will set up a group for each initial permissions role and an extranet group for all users who have access to this particular extranet space.
In addition the app will create an extranet-users group for all users in the system who are assigned to an extranet space.