The terms are a holdout from the 16-bit registry in Windows 3, in which registry keys could not contain arbitrary name/data pairs, but rather contained only one unnamed value (which had to be a string). In this sense, the Windows 3 registry was like a single associative array, in which the keys (in the sense of both ‘registry key’ and ‘associative array key’) formed a hierarchy, and the registry values were all strings. For compatibility with the previous behavior, each registry key may have a "default" value, whose name is the empty string. These settings are stored in CMOS RAM, which makes this information volatile. Therefore, a CMOS battery is used to provide a small trickle of power to the CMOS RAM in order to retain the data even wen the computer is off and unplugged.
If a registry key resides in both locations but conflicts in some way, the data found in the signed-in user’s hive, HKEY_CURRENT_USER\Software\Classes, takes priority and is used in HKEY_CLASSES_ROOT. Due to the complexity of how HKEY_CLASSES_ROOT keys are set up, we absolutely do not recommend that you change default file associations from within the registry. Instead, see How to Change File Associations in Windows for instructions on doing this from within your normal Windows interface. where LOCATION_OF_system.dat is the explicit path to the system.dat file, LOCATION_OF_user.dat is the explicit path to the user.dat file, and REGISTRY_KEY_TO_DELETE is the name of the key you want to delete. The Windows registry is a powerful tool that can be used to fix severe problems.
A Reset option will remove all your personal files and delete any settings or configuration you did on your computer. Windows 8 will reinstall any applications you installed and create a copy of these applications on your desktop, but backup your data before you do a refresh. An Upgrade Install may fix a corrupt registry as this option will install your Windows 7 again without affecting your personal files. An Upgrade Install may fix a corrupt registry as it will install Windows Vista again without affecting your personal files. HKCU – Abbreviated from the registry key name HKEY_CURRENT_USER.
Once Registry Editor has been opened using the appropriate permissions, the HKEY_LOCAL_MACHINE\SAM and HKEY_LOCAL_MACHINE\SECURITY keys can be explored like any other key in the hive. The SECURITY subkey is used to store the security policy of the current user.
HKCU stores settings that are specific to the currently logged-in user. The HKCU key is a link to the subkey of HKEY_USERS that corresponds to the user; the same information is reflected in both locations. Information stored in the Registry is divided into several predefined sections called "hives".
To help prevent any registry disasters, here are five tips to keep in mind when considering an edit of the registry. Windows 10 will reinstall any applications you installed and create a copy of these applications on your desktop, but backup your data before you do a refresh.
It’s linked to the security database of the domain where the user is logged in, or to the registry hive on the local computer if the user is logged in to the local system domain. If you, or someone else, have used Registry Editor before on your computer, you may need to collapse any open registry keys until you find the HKEY_LOCAL_MACHINE hive.
One wrong edit, in the wrong entry, can render a Windows machine unusable or worse — unbootable. So any user who attempts to edit the registry needs to do so with caution.