Generally, a person who has full rights and permissions to all resources on a network.
The administrator is usually responsible for installing, managing, and controlling servers and networking components. Administrators can also modify the properties of user accounts and the membership of groups, create and manage security printers, install printers, share resources, and assign permissions to those resources.
In Microsoft Windows NT and Windows 2000, the Administrator account is a built-in account whose password is defined during installation. In Windows NT, the administrator account is a member of the Domain Admins group and the Administrators group on the domain controller on which it is defined, and it has full rights and permissions on all user-accessible system resources. In Windows 2000, the administrator account is a member of the built-in Administrators group.
You can rename the default Administrator account, but you cannot delete it. If you rename the account, make sure you remember what the new name is!