Every website administrator has complete control over how visitors are able to interact with their site through its advanced permissions interface.
To modify site permissions select the Users & Permissions tab and then the Permissions & Sharing page. This page specifies the privileges that different kinds of visitor have to the entire website, including all applications and content on the site. The administrator can then optionally set up specific privileges for a particular application or piece of content, overriding these defaults.
The default set of visitor types (1 in the diagram) is:
Registered Users - Visitors who are logged in, but are not members of your website.
The Public - Visitors who are not logged in.
<Website Name> Administrators - The administrators of your site (as defined on the Members page).
<Website Name> Members - The members of your website.
For more information on the types of visitor to your site read the People section of the manual.
The available privileges (2) you can grant a group are:
Read - Visitors can read content. If you remove the Read permission from both The Public and Registered Users then only members of your site will be able to view your site.
Contribute - These visitors can contribute content to your site. For example they can post to a discussion forum, or add photos to the gallery. This privilege automatically infers the Read privilege.
Admin - These visitors can carry out administration functions, modifying any part of the site, and accessing the administration interface. This permission infers the Read and Contribute privileges.
Some privileges can not be selected for some visitor types. For example you cannot grant Admin privilege to The Public. Doing so would be dangerous as anyone could edit your website even without logging in!
If the group or person you wish to modify the permissions for is not in the list you may add them via the Add User, Add Group by Name, or Add Group by Category buttons (3). In both these cases the word "group" refers to groups of members of other websites on the system (e.g., you may wish to grant all members of your friend's website the Contribute privilege on your site).
1. A standard publicly readable website would grant the Read privilege to The Public, and Registered Users. It would then grant Contribute to its members so they can upload photos and add comments in the discussion forums etc. The permissions would therefore be configured as:
2. A private website would grant no privileges to The Public or Registered Users. It would then grant the Contribute privilege to the members of the site:
3. An information only site would only grant Read privileges to the members of the site. If public access was required then also grant Read to The Public and to Registered Users, allowing visitors to read content but be unable to add events to calendars or photographs to albums, etc.
It is impossible to remove Admin privileges for the administrators of the site, otherwise as the owner you would not be able to access the administration pages anymore.