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



A Registry Cleaner is a program that scans the Windows Registry and looks for outdated and invalid entries.

Applications often create Registry entries for temporary data and pointers to other files, but never delete them. In addition, if folders are manually deleted by the user, Registry entries may point to files that do not exist. A Registry cleaner can be part of a package of system utilities or a stand-alone program. A registry is designed to remove redundant or unwanted items from the Windows registry. The cleaner program attempts to remove unneeded or unwanted items from the registry.

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 cleaners 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.

Some software and hardware developers use outdated or incorrect installation processes that fail to remove all references to the application or hardware when it is either installed or uninstalled.

Uninstalling or changing software, hardware and drivers never leaves a PC clean. Entries are left behind in the computer registry causing the PC to become unstable and corrupted. This results in sudden crashes, system failures and unknown error messages that ultimately cause a severe lag in the PC's performance.

When software or hardware is uninstalled it is highly probable that remnants are left behind on the hard drive or in the registry that clog up the system. Without a good program to remove and fix these entries there may be problems that cause imminent trouble including:

- Corrupted entries left in the Computer Registry

- Broken links and short cuts

- Program folders, help files, fonts and configuration files

- Applications that load when the PC starts-up

The PC quickly becomes bogged down, causing frustratingly slow performance with random errors messages and even system crashes.

Some OF The Free Registry Cleaners are as follows

* RegistryFix

* Registry Easy

* RegCure

* Error Killer

* Error Nuker

* Regsweep

* Reg Clean

Some OF The Advantages

Registry cleaners, or registry cleanup software, can in some cases improve the performance and reliability of computers by ridding the registry of unnecessary and fragmented files, which can reduce the need for more manual maintenance.

Due to the sheer size of the registry database, manually cleaning up debris and invalid entries would be impractical, so registry cleaners are essentially tools that automate the process of looking for invalid entries or broken links within the registry and removing them.

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.

Some Disadvantages

There are a number of problems with the concept of a registry cleaner. Most notably, there is no reliable way for a program to know whether any particular key is 'junk' or not. Windows is closed source, so registry cleaner designers can not know for sure whether any particular key is still being used by Windows or what detrimental effects removing it may have; leading to examples of registry cleaners causing loss of functionality and, potentially, system instability.

With regards to performance, whilst on Windows 9x computers, it is possible that a very large registry could slow down the computer's startup time; the on-disc structure of the registry is entirely different on the NT line of Operating Systems (including Windows XP and Vista). Slowdown due to registry bloat is thus far less of an issue in modern versions of Windows. More importantly, however, the difference in speed due to the use of a registry cleaner is negligible: rarely do they remove more than a few kilobytes from the total size of the registry. Any potential user of a registry cleaner must thus balance a probably negligible performance increase against a non-zero possibility of system instability.