Whenever a user account is created, Windows NT assigns a unique security identifier (SID) to that account, which the operating system uses to identify the account. If an accidentally deleted account is recreated, the SID will be different even though every visible detail is the same. Consequently, when the user tries to access resources, he or she will have only the permissions granted to the USERS group. To restore the privileges the old account had, the new account must be added to the groups that the old account was a member of, and any resources that granted special privileges to the individual account must be explicitly set to grant those privileges to the replacement account.