Registry software is a term used to describe various applications that browse or manipulate a computer's registry. The registry is a large repository of data that is used by Windows® operating systems to store system configuration information and application settings. Entries are made into the registry when the system is first installed and every time it is modified thereafter when a new application is installed. Over time, the database can become oversized and redundant. Implementing registry software on a computer allows it to scan and repair the registry, optimizing it for better system performance. There are also some types of registry software that enable the user to manually browse the registry and make custom changes to its entries.
The Windows® registry is divided into hives, each corresponding to a domain of information. For example, HKEY_LOCAL_MACHINE is a hive devoted to details concerning a machine’s hardware. Similarly, there are other hives that contain data about plug-and-play devices and specific user preferences, such as start menu settings, desktop icons, logon names and core Windows® operations. As the user customizes the machine and installs third-party applications over time, the registry grows large, and many of the values become redundant. This eventually results in extremely slow system start-ups, system instability, and frequent hard drive crashes.
Most types of registry software analyze the registry for indications of redundancy and clean it up to improve the machine’s performance. It completes this process by checking if the registry has duplicate values, unused keys or values, broken links, or unnecessary configuration details. The software will then remove duplicate values or unused keys, reestablish links, and perform other optimization tasks. Some types of registry software also include a virus scanner that checks if the registry has values entered by a virus or worm. Since the registry is a vital part of the operating system, the software will also backup the current registry so it can be easily restored in case modifications cause unforeseen system issues.
Advanced users may need to interact with the Windows® registry directly to make custom changes to its entries or to browse through its values for application development purposes. In its raw form, however, the registry is incomprehensible. Windows® operating systems come bundled with registry software called "regedit.exe" which allows the user to browse through the registry’s hives with ease and make changes to individual entries. The data is laid out in a hierarchical fashion. Some registry browsers also protect critical registry entries to ensure the user does not accidentally corrupt the database.