User profile
A User Profile (userprofile, or simply 'profile' when used in-context) is a feature of the Microsoft Windows operating system, comprising a given user's collection of personal documents and settings on that computer.
Taking Windows XP as an example, profiles are stored within the "Documents and Settings" folder on the system drive, normally (but not necessarily) the C: drive. Each subfolder of "C:\Documents and Settings" comprises one profile.
Profile Creation
Establishing a user-account on the computer (or on its parent domain) does not, in fact, create a profile for that user. The profile is created the first time the user logs-on at the computer -and this logon has to be at the computer itself, not for example logging-on across a network to access shared folders, which action does not create a profile.
At first logon, a folder will typically be created under "Documents and Settings" matching the logon-name of the user. However, should a folder of that name already exist, then the profile-creation process will not, as you might expect, use the existing data. Instead it will 'sidestep' the pre-existing folder, and creat a new one, typically named username.computername, on workgroup computers, or username.domainname on Active Directory member computers.
Once a profile-folder has been created, Windows will never rename that folder. Thus if the username itself is subsequently changed, the profile-folder will remain as-is, and the profile will no longer match the username, which could lead to confusion. For this reason it is best to avoid renaming user-accounts if at all possible.
The new profile is in fact created by making a copy of a special profile, named Default User. It is permissible to modify this Default User profile (within certain guidelines) so as to provide a customised working environment for each new user. Modification of the Default User profile should ideally be done from new, prior to any users logging-on to the computer; if a user has already logged-on once or more, the Default Profile has no effect whatosever for that user.
Profile Contents
NTUSER.DAT - Within the root of the profile, a file named NTUSER.DAT contains the user's personalised settings for the majority of software installed on the computer, including Windows itself. When the user logs-on, NTUSER.DAT becomes merged with the computer's registry, such that it appears as the HKEY_CURRENT_USER branch of the registry tree. NTUSER.DAT is held open for writing (i.e. 'locked') for the entire time the user remains logged-on, hence somewhat paradoxically this file cannot be copied or backed-up by its owner, but only by another user, whilst the owner is logged-off.
My Documents - Is intended to contain the user's work, and in Windows XP-aware programs, dialog-boxes will typically prompt the user to store documents here. 'My Documents' also as a shortcut also appears on the desktop, and in My computer. It is here that these shortcuts point.
Favorites, Cookies and History - These folders are used by Microsoft's Internet Explorer web-browser to store surfing data. They are not used by alternative browsers such as Firefox or Opera, which typically store their data under "Application Data."
Nethood, Printhood - Contain the network shares and printers 'discovered' by the user with the My Network Places applet, in the form of shortcuts.
Start Menu - contain the shortcuts present on the same-named Desktop feature.
Desktop - Similarly contains files and shortcuts present on the user's desktop.
Application Data is provided mainly for the use of programmers, as a place to store data related to specific software, but which does not fall into the category of documents that a user might open directly. This folder was made necessary by Windows 'good practice' programming guidelines, which now prohibit the storage of temporary data of any kind in the Program Files folder.
Local Settings is functionally similar to Application Data -and in fact it contains a second subfolder of that name. It also contains the temporay files generated by Windows programs themselves, and as a result of Internet Explorer's online activities. For standalone computers the two folders are functionally similar, but on networks employing Roaming Profiles, the Local Settings folder is not included in the profile-synchronization process. Thus, data in the Local Settings folder will not be copied between computers when the user roams.
Note; Some of these subfolders are hidden from the user's view in Explorer. To see them you must uncheck Hide System Folders in the folder-options.
Special Profiles
Default User - Plays a role in the profile-creation process, see above.
All Users - This profile is present mainly to answer an issue related to software installation. It provides a way for setup-programs to create desktop or start-menu shortcuts which will be visible to all users of the computer, not just the user running the setup program. The Application Data section may also contain program-data common to all users. All Users acts purely as an information-store, it is never loaded as an active profile.
Administrator - All versions of NT-based Windows have an Administrator account and corresponding profile, although on XP Home this account may only be visible on the log-on screen if the computer is started in Safe Mode.
History and Origin =
Historically, the Windows 95/98 product line did not employ user-profiling as standard -all users sharing the same settings- although that feature could be activated in Control Panel.
The user-profiling scheme in force today owes its origins to Windows NT, which stored its profiles within the system folder itself, typically under C:\WINNT\Profiles\. Windows 2000 saw the change to a separate "Documents and Settings" folder for profiles, and in this respect is virtually identical to Windows XP.
New Developments
Windows Vista's profiles are functionally similar to those of Windows XP, but with some differences. Perhaps the key difference is that they are stored in a "C:\Users" folder, instead of "C:\Documents and Settings." Therefore, to cater for programs which are not Vista-ready (read: most exisitng software) a symbolic-link is also provided under the name of "Documents and Settings" which invisibly redirects any attempted access of the latter to "C:\Users." Inital experiences of the author in testing Vista suggest that this folder-redirection mechanism is potentially a source of trouble, and that it would have been better to have retained the previous scheme. The fact that the profile-root folder appears twice in any folder-listing also has adverse implications for any backup program. Backup software needs to be aware of this Vista idiosyncracy, or else it is likely to double to size of the backup for no good reason, by copying what appear to be two separate folders, both containing the bulk of the data on the computer.
A second change in Vista is that the media-specific "My Pictures" and "My Music" folders are now outside of the "My Documents" folder, instead of being subfolders.
References:
Anteaus 17:38, 29 April 2007 (UTC)