User accounts are required for users to access resources in a Windows Server 2003 environment.

Groups enable the assigning of permissions and rights. By assigning permissions to a group, all group members inherit the same permissions.

Machine accounts provide authentication and auditing for machines used in a domain.

Active Directory Users and Computers is a graphical tool used to create and manage Active Directory objects such as users, groups, and machines.

dsadd.exe can add computers, contacts, groups, OUs, users, and quotas.

dsget.exe shows the properties of objects in Active Directory. It works with computers, contacts, subnets, groups, OUs, servers, sites, users, quotas, and partitions.

dsmove.exe moves objects within Active Directory.

dsquery.exe enables you to query all Active Directory objects for a set of objects that match a specified criterion.

gpresult.exe displays Resultant Set of Policy (RSoP). RSoP shows the effective policy for a particular user and a specified machine.

whoami.exe displays the username and group membership information about the currently logged-on user.

cmdkey.exe enables you to configure and manage stored usernames and passwords from the command line.

You can create user accounts from within the GUI using ADUC.

You can create user accounts from the command line using the dsadd command.

You can use ldifde and csvde files to import and export users from Active Directory.

You can use dsmode to manage user account properties...