User Account Control
In Windows NT and later systems derived from it (such as Windows 2000, Windows XP, Windows Server 2003, and Windows Vista/7/8/10), there must be at least one administrator account (Windows XP and earlier) or one able to elevate privileges to superuser (Windows Vista/7/8/10 via User Account Control). In Windows XP and earlier systems, there is a built-in administrator account that remains hidden when a user administrator-equivalent account exists. This built-in administrator account is created with a blank password. This poses security risks as local users would be able to access the computer via the built-in administrator account if the password is left blank, so the account is disabled by default in Windows Vista and later systems due to the introduction of User Account Control (UAC). Remote users are unable to access the built-in administrator account.