Caution: If you are not sure which registry key you need to modify, better don´t do it. Always do backup first. Incorrect modify registry key can cause windows malfunction or others unknown problem. These problems might require that you reinstall the operating system.

Since windows 98, Microsoft introduce registry to manage parameters for application. Before registry introduce, almost windows application manage parameter by saving into file with extension ini. Every application have they are ini files.

The Microsoft Computer Dictionary, Fifth Edition, defines the registry as:

“A central hierarchical database used in Microsoft Windows 98, Windows CE, Windows NT, and Windows 2000 used to store information that is necessary to configure the system for one or more users, applications and hardware devices.”

“The Registry contains information that Windows continually references during operation, such as profiles for each user, the applications installed on the computer and the types of documents that each can create, property sheet settings for folders and application icons, what hardware exists on the system, and the ports that are being used.”

Registry is a central database repository for any modern windows application, since any application write the key and value in the registry database repository; the database will be bigger and bigger. That´s related to windows performance, since entire windows system and windows application will be read on the same place since windows boot and application startup. When you are uninstall application which you are don´t need or when application crash in middle of write or delete registry there probably making unused registry key in registry database repository, that´s a lot of cumulative unused registry key in your registry repository database since first time you are install windows. There is almost impossible manual check which the registry key is unused. To do remove unused registry key in registry repository, you can use software like Speedy PC Pro. Here you can download Speedy PC Pro by click on this .

Since first time windows introduce registry, by the normal windows not provide shortcut for registry tools. It´s not like others system tools you can find on control panel and its little bit or almost nothing about registry help on windows. When talking about registry, it´s almost for advance windows users.

Every registry has a key,subkey and value, they are store like file directory. Key for registry was write like example : HKCU\software\Microsoft\Notepad

There are five standard root key come from windows since first install :

• HKEY_CLASSES_ROOT (HKCR)
• HKEY_CURRENT_USER (HKCU)
• HKEY_LOCAL_MACHINE (HKLM)
• HKEY_USERS (HKUS)
• HKEY_CURRENT_CONFIG (HKCC)

Here Some tools provide by windows for modify registry was: regedit.exe, regedt32.exe, reg.exe and file with extension reg. Regedit.exe, regedt32.exe and reg.exe almost have similar function for edit the registry. Regedit.exe and regedt32.exe is windows Graphic User Interface (GUI) registry editor, the main different between regedit.exe and regedt32.exe is regedt32.exe provide function for set permission for user to read registry key. You can find regedit.exe on %SystemRoot% and regedt32.exe on %SystemRoot%\System32 which generally for some standard windows installed %SystemRoot% was c:\windows directory. Reg.exe is a console registry editor which provides function similar to regedit.exe.

Backing up the Registry

Here example how to using regedit.exe for backup windows registry :
If you are using windows xp,vista click start->run and type %SystemRoot%\regedit.exe, if you are using windows 7, click start and type %SystemRoot%\regedit.exe

If you are running correct, you should be seeing like this:


Note: the screen for the root key is for user has all permission to read entire root key, if you screen for the rootkey is not same, probably you don´t have permission to read.

Regedit provide function for export and import, for purpose backup we can use export function. Click on computer and either you can click file->export or right click and click export. After click export will be popup one option for place saving the file. You can save the registry backup file in the directory in anywhere you want.For restore the registry file you can use import function in the regedit file menu

For more information about windows registry you can go to : http://support.microsoft.com/kb/256986