What is Window Registry ?

 

The Windows Registry is a hierarchical database that stores configuration settings and options on Microsoft Windows operating systems. It contains settings for low-level operating system components as well as the applications running on the platform: the kernel, device drivers, services, SAM, user interface and third party applications all make use of the registry.

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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.

What is the Windows Registry Used For?

The Windows Registry is used to store much of the information and settings for software programs, hardware devices, user preferences, operating system configurations, and much more.

In many ways, the registry can be thought of as a kind of DNA for the Windows operating system.

How to Access the Windows Registry?

The Windows Registry is accessed and configured using the Registry Editor program, a free registry editing utility included with every version of Microsoft Windows.

Registry Editor can be accessed by executing regedit from the Command Prompt or from the search or run box from the Start menu. See How To Open Registry Editor if you need help.

Registry Editor is the face of the registry, and is the way to view and make changes to the registry, but it’s not the registry itself. Technically, the registry is the collective name for various database files located within the Windows installation directory.

Windows Registry Availability?

The Windows Registry and the Microsoft Registry Editor program are available in nearly every Microsoft Windows version including Windows 7, Windows Vista, Windows XP, Windows 2000, Windows NT, Windows 98, Windows 95, and more.

The following table lists the predefined keys that are used by the system. The maximum size of a key name is 255 characters.

Folder/predefined key	Description
HKEY_CURRENT_USER	Contains the root of the configuration information for the user who is currently logged on. The user’s folders, screen colors, and Control Panel settings are stored here. This information is associated with the user’s profile. This key is sometimes abbreviated as “HKCU.”
HKEY_USERS	Contains all the actively loaded user profiles on the computer. HKEY_CURRENT_USER is a subkey of HKEY_USERS. HKEY_USERS is sometimes abbreviated as “HKU.”
HKEY_LOCAL_MACHINE	Contains configuration information particular to the computer (for any user). This key is sometimes abbreviated as “HKLM.”
HKEY_CLASSES_ROOT	Is a subkey of HKEY_LOCAL_MACHINE\Software. The information that is stored here makes sure that the correct program opens when you open a file by using Windows Explorer. This key is sometimes abbreviated as “HKCR.” Starting with Windows 2000, this information is stored under both the HKEY_LOCAL_MACHINE and HKEY_CURRENT_USER keys. The HKEY_LOCAL_MACHINE\Software\Classes key contains default settings that can apply to all users on the local computer. The HKEY_CURRENT_USER\Software\Classes key contains settings that override the default settings and apply only to the interactive user. The HKEY_CLASSES_ROOT key provides a view of the registry that merges the information from these two sources. HKEY_CLASSES_ROOT also provides this merged view for programs that are designed for earlier versions of Windows. To change the settings for the interactive user, changes must be made under HKEY_CURRENT_USER\Software\Classes instead of under HKEY_CLASSES_ROOT. To change the default settings, changes must be made under HKEY_LOCAL_MACHINE\Software\Classes. If you write keys to a key under HKEY_CLASSES_ROOT, the system stores the information under HKEY_LOCAL_MACHINE\Software\Classes. If you write values to a key under HKEY_CLASSES_ROOT, and the key already exists under HKEY_CURRENT_USER\Software\Classes, the system will store the information there instead of under HKEY_LOCAL_MACHINE\Software\Classes.
HKEY_CURRENT_CONFIG	Contains information about the hardware profile that is used by the local computer at system startup.