Site Security
As an administrator you have the responsibility of managing who can access resources on your site. Windows SharePoint Services enables you, as a site owner, to control what users or groups of users can access your SharePoint sites. Site security is managed through the use of SharePoint groups.
Tip: Root site permissions and the permissions of subsites that inherit from the
roots sites are accessed and managed in the same way. Subsites that contain unique
permissions and do not inherit from the root site will be accessed and managed uniquely in
some instances. Keep this in mind when you plan and manage your site security.