The Enterprise Admin portlet is used for most administrative tasks. This portlet has an interface for the creation and maintenance of the following:
Users
Organizations
User Groups
Roles
Additionally, it allows you to configure many server settings, including:
Information about the site
Authentication options, including Single Sign-On and LDAP integration
Default User Associations
Reserved Screen Names
Mail Host Names
Email Notifications
You need to use the Enterprise Admin portlet to create your portal structure, implement security, and administer users. Only the users with the Administrator role has permission to add the Enterprise Admin portlet to a page.