Windows NT allows multiple users to work on the same computer while retaining their individual settings. Each user has a unique username, and each user has a user profile.
A user profile is a group of files, folders, and registry entries that "belong" to the user. This includes environment settings (saved as registry keys) such as colors, background, shortcuts, Start menu shortcuts, temporary Internet files, Internet Favorites, user-specific program settings, and other files.
By default, NT stores all profiles in the X:\WINNT\Profiles\%username% folder, where X:\WINNT is the directory that contains Windows NT, and %username% is the username of each user. In addition to directories for each user, you also have two other folders: All Users and Default User.
The All Users folder includes the settings and shortcuts available to all users. For example, if you want all users to have a shortcut to a particular program on the Start menu, you can place the shortcut to it in the All Users folder.
On the other hand, NT only uses the Default User folder when a user logs on to a computer for the first time. NT creates a copy of this folder and saves it in the Profiles directory under the user's name. At the second logon, the user has his or her own profiles folder.
You'll also find the Ntuser.dat file in each profile folder. This file includes the user registry settings that map to HKEY_CURRENT_USER when the user logs on. You can open the Ntuser.dat file in the Registry Editor and check the settings.
Note: Editing the registry is risky, so be sure you have a verified backup before making any changes.