The Windows registry is basically a directory. It stores settings for the operating system for Windows Mobile, 64-bit versions and Microsoft Windows 32-bit versions. It contains information and settings for all the operating system software, hardware, most non-operating system software, users and preferences of the PC. Whenever a user makes changes to Control Panel settings, system policies, file associations or installed software, the changes are reflected and stored in the registry.

The registry also provides a window into the operation of the kernel, exposing runtime information such as performance counters and currently active hardware. This use of registry mechanism is conceptually similar to the way that Sysfs and procfs expose runtime information through the file system (traditionally viewed as a place for permanent storage), though the information made available by each of them differs tremendously.

The Windows registry was introduced to tidy up the profusion of per-program INI files that had previously been used to store configuration settings for Windows programs. These files tended to be scattered all over the system, which made them difficult to track.

The Registry is stored in several files; depending upon the version of Windows, there will be different files and different locations for these files, but they are all on the local machine, except for the Ntuser.dat files. There is one such file per user that contains the information in HKEY_CURRENT_USER; it may be placed on another computer to allow for roaming profiles. The policy file, which is usually stored on a server in the local network, may also be located remotely.

What is a Registry Cleaner?

A registry cleaner is a type of program for Microsoft Windows operating system designed to remove redundant or unwanted items from the Windows registry. The cleaner program attempts to remove unneeded or unwanted items from the registry.

What Problems Does it Solve?

Some uninstallers for Windows software do not completely remove all traces of the software from the registry. Depending on the technical details, these traces can interfere with performance or have other negative impacts. Using a registry cleaner is one of the only ways to get rid of these bits. The registry cleaner scans the registry, and picks out the unnecessary and/or damaged pieces and deletes/repairs them.

Registry cleanup software: The Solution!

Registry cleaners, or registry cleanup software, can often improve the performance and reliability of computers by ridding the registry of unnecessary and fragmented files, which can dramatically reduce the need for serious maintenance. Some registry cleaners offer backup and restore functions that allow the user to revert changes made by the registry cleaner in case they are undesired.

List of Available Software:

Pimasoft Registry Fix

SmartPCTools Software Registry Repair Wizard 2007

VCOM Fix-it Utilities

Sysfixmaster Registry Cleaner

While this article is too short to go into complete details about registry cleaners, hopefully you have a good place to start your education. I have listed several great references and the end of this article. You can also visit http://www.registrycleanerauthority.com/

Windows 2000 Registry: Latest Features and APIs Provide the Power to Customize and Extend Your Apps.

Chen, R. The Old New Thing, Addison-Wesley, 2007, p. 322.

Microsoft's Windows 2000 Security Hardening Guide version 1.3, published May 15, 2003