Windows registry

The Windows Registry is a hierarchical database that stores low-level settings for the Microsoft Windows operating system and for applications that opt to use the Registry. The kernel, device drivers, services, Security Accounts Manager (SAM), and user interface can all use the Registry. The Registry also allows access to counters for profiling system performance.

In simple terms, The Registry or Windows Registry contains information, settings, options, and other values for programs and hardware installed on all versions of Microsoft Windows operating systems. For example, when a program is installed, a new subkey containing settings like a program's location, its version, and how to start the program, are all added to the Windows Registry.

When introduced with Windows 3.1, the Windows Registry primarily stored configuration information for COM-based components. Windows 95 and Windows NT extended its use to rationalise and centralise the information in the profusion of INI files, which held the configurations for individual programs, and were stored at various locations. It is not a requirement for Windows applications to use the Windows Registry. For example, .NET Framework applications use XML files for configuration, while portable applications usually keep their configuration files with their executable.

Prior to the Windows Registry, .INI files stored each program's settings as a text file, often located in a shared location that did not provide user-specific settings in a multi-user scenario. By contrast, the Windows Registry stores all application settings in one logical repository (but a number of discrete files) and in a standardized form. According to Microsoft this offers several advantages over .INI files. Since file parsing is done much more efficiently with a binary format, it may be read from or written to more quickly than an INI file. As well, strongly typed data can be stored in the Registry, as opposed to the text information stored in .INI files. This is a benefit when editing keys manually using regedit.exe, the built-in Windows Registry editor. Because user-based Registry settings are loaded from a user-specific path rather than from a read-only system location, the Registry allows multiple users to share the same machine, and also allows programs to work for less privileged users. Backup and restoration is also simplified as the Registry can be accessed over a network connection for remote management/support, including from scripts, using the standard set of APIs, as long as the Remote Registry service is running and firewall rules permit this.

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