In Microsoft Windows NT, a built-in account with a null password created during installation. The Guest user account is a member of the Domain Guests global group on the domain controller or member server on which it is defined.
The Guest account is intended for occasional users who need temporary access to resources on the network. It is disabled by default and can be enabled using User Manager for Domains. The Guest account is also created by default on machines running Windows 2000 during installation.
On a Windows NT domain controller, the Guest account is a global user account; a member server or Windows NT workstation has a separate Guest local user account. To control guest access to your network, you can assign these Guest accounts one, both, or neither of the following rights:
Do not enable the Guest account unless you are sure you will need it; unless you are sure that all your shared resources have correct permissions assigned to them, enabling the Guest account could pose a security risk.