Every user profile created on a Windows operating system has an NTUSER.DAT file. A user profile contains personal files and preference settings that are specific to each user. For example, each user profile contains a unique Documents folder, Start Menu configuration, desktop properties, browsing history, etc.
This is a registry file kept in the registry and not in your documents. It contains personnel settings for each user. Leave this file alone.
NTUSER.DAT
(b) ntuser.Dat
its a .dll file that provides API functions to your user profile.. like JAVA API functions..
A Roaming profile is where setting established by a user at one computer are stored in a file on a file server on the network and shared with all computers in the workgroup, When a user moves from one computer to the next in the workgroup the roaming profile follows the user so that he or she does not have to redo settings at each computer. A Mandatory profile is a roaming profile that applies to all users in a user group, and individual users cannot change that profile. It is used in situations were users perform only specific job-related task.
Default user
a mandatory A local user profile is stored on the computer to which the user logs on.
If referring to WIndows 7 User Profile C:\Users let you move user files from one profile to another if your's have administrator rights. To manage settings navigate to Control Panel\User Accounts and Family Safety\User Accounts\Manage Accounts
The user profile name identifies the user to the server. This user profile name is also known as the user ID. It is the name the user types in the User prompt on the Sign On display.
a user profile that prevents the user from logging on if the mandatory profile is unavailable
the user profile settings like the wallpaper, desktop icons, application settings etc are stored in the ntuser.dat. This is similar for both local and roaming profiles.
registry