The Basics of Windows Registries

Most computer users will have no idea what the Windows registry is or does, and yet it is central to the whole functioning of a Windows computer. Most people will only get to know about it when they discover that they have a problem with it.

It is always a good idea to have some knowledge about the Windows registry, even if you are never going to use it. Knowing about the registry though is not an excuse do try some manual editing of it, even experienced IT technicians do not like messing around with the registry, they know just what damage can be done with manual alterations.

The Windows Registry

The Windows registry is the main storage device for all of the computer’s configuration data, and is used to store all the information about the operating system, hardware and software installed on the machine. It also includes all of the user preferences used to make the computer friendly to work on. The Windows operating system will constantly read the information stored in the registry to make programs and applications work as they should.

New entries in the registry can be automatically created by the Windows operating system, or can be added and changed with the modification of hardware and software on the machine. The latest Windows registries are continuations of the first registry, as brought out with the release of Windows 95. Prior to Windows 95, configuration data was held in a INI filing system that meant that files were spread out across the whole computer, rather than centralised. The INI filing system though served the same purpose as the modern registry. The fact that the files were spread out meant that it could often be difficult to pinpoint where an error lay, making a repair much more difficult.

The Modern Registry

Windows registries are strictly organised and have a hierarchy to the contents. Just as a word document could be stored in My Documents\Word\Doc1.doc, so registry entries are stored Key\Subkey\Value.

Within the registry there are six main storage areas -

» HKEY_CLASSES_ROOT
» HKEY_CURRENT_CONFIG
» HKEY_CURRENT_USER
» HKEY_DYN_DATA
» HKEY_LOCAL_MACHINE
» HKEY_USERS

You will probably have come across registry entries as they are stored on a computer’s hard drive in System.dat and User.dat files. The System.dat files contain system information relating to such things as hardware configuration data, whilst User.dat files contain user preferences.

If you are using an older version of Windows, like Windows ME, then there are also additional files known as Classes.dat, which stored the HKEY_CLASSES_ROOT data.

The Storage Areas

HKEY are also known as keys, and although there are six main root keys (as listed above); there are only two actual keys, which are HKEY_USERS and HKEY_LOCAL_MACHINE. The other four root keys act like dummies or shortcuts for information. HKEY_CLASSES_ROOT, HKEY_CURRENT_CONFIG and HKEY_CURRENT_USER are just shortcuts to entries held in HKEY_USERS and HKEY_LOCAL_MACHINE.

The last key, HKEY_DYN_DATA in the strictest sense isn’t a key as it contains information about the current device status. The information stored here changes every time a computer restarts.

• HKEY_CLASSES_ROOT – this folder is used to store information about file extensions, like .doc .exe and .txt. Additionally it stores CLSIDs, IIDs, and ProgIDs to ensure that there is linkage to 16 bit Windows.

• HKEY_CURRENT_CONFIG – contains data about plug and play devices, as well as multiple hardware settings. Information comes from HKEY_LOCAL_MACHINE\Config

• HKEY_CURRENT_USER – stores all preference settings for the current user of the computer, obtaining all information from HKEY_USERS

• HKEY_DYN_DATA – this key relates to the current settings for the computer session in progress

• HKEY_LOCAL_MACHINE – contains all information about the machine being used, and as such is used by all computer users.

• HKEY_USERS – This file contains all of the information about preferences and customised settings. This can be user specific or computer settings. Within the folder there are subkeys, like HKEY_USERS\DEFAULT, which have default settings, although every time a new user is set up on a machine there is a new subkey formed, where information then gets moved to the HKEY_CURRENT_USER key

More details can be discovered about the registry from Wikipedia’s Windows Registry article.

The Best Registry Repair Software

If you are in need of the best registry cleaner to deal with your registry issues, then there is no better product than RegCure from ParetoLogic. A full review of RegCure is available from our site and RegCure can even be tried as free download that will scan the registry.