Updated: 12/26/2023 by Computer Hope
Windows registry

The registry or Windows registry is a database of information, settings, options, and other values for software and hardware installed on all versions of Microsoft Windows operating systems. When a program is installed, a new subkey is created in the registry. This subkey contains settings specific to that program, such as its location, version, and primary executable.

When Windows was released (e.g., Windows 3.11), it relied heavily on .ini files to store Windows and Windows programs configurations and settings. Although .ini files are still sometimes used, most Windows programs rely on settings made to the Windows registry after being installed.

Information about the Registry Editor

To view and make changes to the Windows registry, the Windows Registry Editor (shown below) may be used. In Windows 3.x, the Registry Editor was known as the Registration Info Editor or Registration Editor. The Registry Editor lets you view all keys and values that are in the registry, and change Windows, program, or driver values you feel are necessary.

Microsoft Windows Registry Editor

Registry root keys (hive name)

When first opening the Windows Registry Editor, it displays root keys that contain all registry values. Below is a brief description about each of the most common root keys and the values contained in each of them.

Root Key Description
HKCR (HKEY_CLASSES_ROOT) Describes file type, file extension, and OLE (Object Linking and Embedding) information.
HKCU (HKEY_CURRENT_USER) Contains user who is currently logged in to Windows and their settings.
HKLM (HKEY_LOCAL_MACHINE) Contains computer-specific information about the hardware installed, software settings, and other information. The information is used for all users who log on to that computer. This key, and its subkeys, is one of the most frequently areas of the registry viewed and edited by users.
HKU (HKEY_USERS) Contains information about all the users who log on to the computer, including both generic and user-specific information.
HKEY_CURRENT_CONFIG (HKCC) The details about the current configuration of hardware attached to the computer.
HKDD (HKEY_DYN_DATA) Only used in Windows 95, 98, and NT, the key contained the dynamic status information and plug and play information. The information may change as devices are added to or removed from the computer. The information for each device includes the related hardware key and the device's current status, including problems.

Windows registry values

Below are the different values you encounter while in the Windows registry and a brief description about what type of data each value can contain.

Icon Type Name Description
Registry closed key icon   Closed key Like the folders seen in Windows Explorer. These keys are what contain the registry subkeys mentioned below.
Open key folder icon   Open key When a key is opened, the icon changes to an expanded or open folder and displays all its contents and any additional subkeys.
Registry REG_SZ icon REG_SZ String value Allows for any string value to be defined on a single line, such as a file path, and is the most commonly found subkey in the registry.
Registry REG_MULTI_SZ icon REG_MULTI_SZ String array value Any multi-line string value.
Registry REG_EXPAND_SZ icon REG_EXPAND_SZ Expanded string value Contains a string with environmental or system variables that need to be expanded. For example, c:\%windir%\example.exe could be the same as C:\windows\example.exe.
Registry REG_BINARY binary icon REG_BINARY Binary value Allows for attributes to be defined in binary as either on or off (0 or 1).
Registry REG_DWORD icon REG_DWORD DWORD value Like the binary value, but capable of values being defined in either 32-bit decimal or hex.
Registry REG_QWORD icon REG_QWORD QWORD value Like the DWORD, but stored as a 64-bit value.

Should I use "registry" or "Registry" in my writing?

According to the Microsoft Manual of Style, "registry" is written entirely in lowercase, except when part of a named system component (e.g., "Registry Editor"), or it's the first word of a sentence.

Database, GUID, Hive, Operating system terms, Registry cleaner, Windows Accessories