Uninstaller

A uninstaller or deinstaller is a computer program which is designed to remove all or parts of a specific other program or application. It is the opposite of an installer. Some software vendors ship an uninstaller with their applications.

A third-party uninstaller is a program which uninstalls programs from vendors different from the uninstaller vendor. Such uninstallers often aim to support uninstallation of a number of programs.

Specialized uninstallers are usually not needed on a computer system which supports package management, provided that software is installed as a properly-built package.

Components

Generally, most (third-party) uninstallers contain the following components:
* Logger: The Logger is used to log installations (e.g., log which files were added or changed, which registry entries were added or changed, etc. at the time of installation). This log is used when the user decides to uninstall the logged installation at later date (in that case, the log is "reversed" -- i.e., the log is read, but opposite actions are taken in reverse order),
* Uninstaller The Uninstaller is used to reverse changes in the log. This way, the applications can be uninstalled because all changes that were made at the times of installation are reversed.
* Analyzer (optional) The Analyzer is used to uninstall programs of which installation is not logged by the uninstaller. In that case, the program analyzes the program and finds (and deletes, if the user decided to uninstall the program) all related files and registry entries,
* Watcher (optional) The Watcher watches running programs for installation programs (and usually offers to start the logger when such programs are detected). Usually, this works by watching the tasklist for any names that are usually used by installation programs (e.g., SETUP.EXE, INSTALL.EXE, etc.)
* Other tools (optional) Some uninstallers may also contains other related tools like a junk file cleaner, browser history cleaner, cache cleaner, etc. These tools are not mandatory for uninstallers and are added mainly to improve the merchantability (since pure uninstallers are unpopular today).

Operations

Usually, in most (third-party) uninstallers, the following operations can be performed:
* Log: watches any changes made to the system during installation,
* Uninstall: uninstalls a program (based on the log or analysis),
* Move/Transport: backs up a program (usually packs all required files and registry entries in a "transport package", which can be transported and installed in another computer) and uninstalls them,
* Archive: backs up a program (and possibly pack them, to save disk space) and uninstalls them,
* Backup: backs up a program (for reinstallation at a later date should the program fail),
* Other related operations: like junk file cleaning, cache cleaning, etc.

Third-party uninstallers today

Nowadays, pure third-party uninstallers (uninstallers that only contain basic components -- that is the watcher, logger, uninstaller, and probably the analyzer) generally are unpopular and are not needed anymore, because:
* Most software programs come with their own uninstallers (which are generally better and more accurate),
* Most uninstallers are not entirely accurate (most of them are known to leave leftovers, which should be deleted by uninstallers),
* There are many better and safer tools that can be used to replace uninstallers,Because of this, to make uninstallers more merchantable, most (if not all) of today's uninstallers contain other related tools (such as a cache cleaner, a junk file cleaner, etc.)

Why the third-party uninstallers are still used today:
* More complex installed programs make system changes that the authors forget, ignore or are not aware. They often integrate third-party components with no thought of their uninstallation. The competition to release new software versions with additional features leave the uninstallation with a very small amount of attention and testing. The accuracy of the integrated uninstallers commonly leave much to be desired.
* The uninstallers that don't contain a logger module are aggressively promoted on the market claiming that completely uninstall programs (a task that is impossible and even dangerous without monitoring installation)
* Many programs are bundled with all kind of add-ons, spyware or not, that are intentionally left on the user's computer after uninstallation of the main program.
* At this time-- when adware, spyware, keyloggers, trojans and other Internet threats appear every day-- installation of a software product from an unknown source is a great risk. When things go wrong with a newly installed program, an uninstaller with a logger module can prove invaluable.

History of uninstallers

The original uninstall concept was created by Jack Bicer in 1992Fact|date=February 2008, while he was working on the Norton Desktop for Windows (NDW) product at the Peter Norton group at Symantec. Frustrated by the unstable software (Windows 3.0/3.1 with NDW), users and developers were frequently wiping out their hard disks, reinstalling Windows and their applications. Bicer, who was working on the installation program for Norton Desktop for Windows, came up with the uninstall concept and developed the first uninstaller.

Ken Spreitzer wrote the PC program called "UnInstaller", first licensed to MicroHelp and now (Feb 1998) sold by CyberMedia. After writing the program, Mr. Spreitzer went on to found Maximized Software.

ee also

* Installer
* Utility program
* Application program
* IBM PC
* Installation (computer programs)
* Operating system
* Computer program
* Computer software