Windows Registry is nothing but a central database used to store Windows settings, application settings, and other vital information in the Windows operating system. When the Windows operating system is running, it continuously refers to the information saved in Registry, and because of this, a corrupt Registry might stop Windows from booting.
Since almost every information is saved in the Registry and there is a dedicated Registry Editor in Windows operating system, many users often manually edit the Registry to make necessary changes to the operating system.
The built-in Registry Editor allows users to create a backup of a specific key or value so that users can easily revert changes made to the Registry. After selecting a Registry key or value, one can click the File menu and then click the Export button to backup the selected key or value. The backup file of Registry is saved with .REG extension, and you can double-click on the .REG file to restore the information back into the Registry.
Where are the Registry files stored?
Maybe you are troubleshooting an unbootable computer or want to backup all Registry hives before formatting the drive so that you can easily restore your personalization settings on your new Windows install.
Registry hives are located in the Windows\System32\Config folder. That is, for instance, if Windows is installed on drive “C,” you can find Registry hives by navigating to C:\Windows\System32\Config folder.
And when opening the Config folder for the first time, you will get a dialog with “You don’t currently have permission to access this folder” message. You just need to click the Continue button to gain access to the folder. This is a one-time prompt, and Windows will not display the prompt the next time you try to access the Config folder.
As you can see in the picture above, the Registry is not a single file. Each Registry Hive has a couple of supporting files, and all supporting files except for HKEY_CURRENT_USER are saved in the Config folder. Supporting files for HKEY_CURRENT_USER are stored in your profile folder.
To know which file supports which hive, check out the following table.
| Registry Hives | Supporting files |
| HKEY_LOCAL_MACHINE\Software | Software, Software.log, and Software.sav |
| HKEY_LOCAL_MACHINE\System | System, System.alt, System.log, and System.sav |
| HKEY_LOCAL_MACHINE\SAM | Sam, Sam.log, and Sam.sav |
| HKEY_LOCAL_MACHINE\Security | Security, Security.log, and Security.sav |
| HKEY_USERS\DEFAULT | Default, Default.log, and Default.sav |
| HKEY_CURRENT_CONFIG | System, System.alt, System.log, System.sav, Ntuser.dat, and Ntuser.dat.log |
How to open Registry files located in the Config folder?
The Registry hives located in the Config folder of the Windows operating system can be opened using the built-in Registry Editor or any other third-party Registry Editing software.
We recommend you visit this page of Microsoft for in-depth information on Windows Registry.