The HKEY_LOCAL_MACHINE\SAM key contains the user and group account information in the directory services database (formerly known as the Security Account Manager, or SAM) for the local computer. For a computer that is running Windows NT Server, this key also contains security information for the domain. This information appears in User Manager. Also, on computers with NTFS partitions, you can view and edit security information for a file in Windows NT Explorer. (From the File menu, click Properties, then click the Security tab. Click Permissions to modify user and group permissions in the directory services database.)
This key is mapped to HKEY_LOCAL_MACHINE\Security\SAM, so changes made in one Registry key also appear in the other.
Caution Do not edit the value entries in this subkey by using Registry Editor. The values are in binary format. Errors in this database may prevent users from being able to log on to the computer.
System administrators should use User Manager (Windows NT Workstation) or User Manager for Domains (Windows NT Server) to add or remove users, to change information about accounts, or to change security information for the local computer or for the domain.