The registry is a system-defined database in which applications and system components store and retrieve configuration data. The data stored in the registry varies according to the version of Microsoft Windows. The kernel, device drivers, services, SAM, user interface and third-party applications can all make use of the registry.
There are five predefined root keys in Windows 8:
- HKEY_CLASSES_ROOT
- HKEY_CURRENT_USER
- HKEY_LOCAL_MACHINE
- HKEY_USERS
- HKEY_CURRENT_CONFIG
1. HKEY_CLASSES_ROOT
HKEY_CLASSES_ROOT contains information about registered applications, such as file associations and OLE Object Class IDs, tying them to the applications used to handle these items. The file type subkeys in HKEY_CLASSES_ROOT have the same name as the file name extension for the file type, such as .exe. File type associations are stored in the registry, but you should use Windows Explorer to change them.
2. HKEY_CURRENT_USER
The HKEY_CURRENT_USER key is a link to the subkey of HKEY_USERS that corresponds to the user; the same information is accessible in both locations. On Windows NT-based systems, each user’s settings are stored in their own files called NTUSER.DAT and USRCLASS.DAT inside their own Documents and Settings subfolder. The mapping between HKEY_CURRENT_USER and HKEY_USERS is per process and is established the first time the process references HKEY_CURRENT_USER. The mapping is based on the security context of the first thread to reference HKEY_CURRENT_USER. If this security context does not have a registry hive loaded in HKEY_USERS, the mapping is established with HKEY_USERS\.Default.
3. HKEY_LOCAL_MACHINE
Registry entries subordinate to this key define the physical state of the computer, including data about the bus type, system memory, and installed hardware and software. It contains subkeys that hold current configuration data, including Plug and Play information, network logon preferences, network security information, software-related information, and other system information.
4. HKEY_USERS
Registry entries subordinate to this key define the default user configuration for new users on the local computer and the user configuration for the current user.Each time a new user logs on to a computer, a new hive is created for that user with a separate file for the user profile. This is called the user profile hive. A user’s hive contains specific registry information pertaining to the user’s application settings, desktop, environment, network connections, and printers. User profile hives are located under the HKEY_USERS key.
5. HKEY_CURRENT_CONFIG
Contains information about the current hardware profile of the local computer system. The information under HKEY_CURRENT_CONFIG describes only the differences between the current hardware configuration and the standard configuration.
FAQ – Windows Registry Editor
Q: What is the Windows Registry?
A: The Windows Registry is a hierarchical database that stores configuration settings and options for the Windows operating system.
Q: How do I open the Windows Registry?
A: To open the Windows Registry, you can use the Windows Registry Editor, which is a built-in tool in the Windows operating system.
Q: What is a registry key?
A: A registry key is a container that stores configuration settings and information in the Windows Registry. It is similar to a folder that holds multiple values.
Q: How can I edit the Windows Registry?
A: You can edit the Windows Registry by using the Windows Registry Editor. It allows you to modify or delete registry keys and values to make changes to the operating system’s configuration.
Q: What is a registry value?
A: A registry value is a specific piece of data stored within a registry key. It can hold various types of information, such as numbers, text, or binary data.
Q: How do I back up my registry?
A: To back up your registry, you can use the Windows Registry Editor to export the entire registry or specific registry keys and values to a file. This backup file can be used to restore the registry if any issues arise.
Q: Can I use the Windows Registry to make changes to my operating system?
A: Yes, you can use the Windows Registry to make changes to your operating system’s configuration settings. However, it is important to be careful when making changes as incorrect modifications can cause system instability or errors.
Q: Is it recommended to use a registry cleaner?
A: The usefulness of registry cleaners is a matter of debate. While they claim to improve system performance by removing unnecessary entries, they can also remove valid or necessary entries, which may lead to system issues. It is recommended to use caution when using registry cleaners.
Q: What versions of Windows have a registry file?
A: The Windows Registry is a feature found in various versions of the Windows operating system, including Windows 95, Windows 98, Windows XP, Windows Vista, Windows 7, Windows 8, Windows 10, and Windows 11.
Q: What kind of information does the registry contain?
A: The registry contains configuration settings, options, and other information related to the Windows operating system and installed software. It stores data in the form of registry keys and values.
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