Windows Registry

The Windows registry contains all the configuration data needed in order to run a Windows based operating system. In order for an application to run, it must first consult the registry. This component of a computer must be regularly maintained in order to keep a computer safe and running at optimal speeds. Maintenance is also necessary in order to avoid crashes and prevent the computer from freezing.

Despite being the most critical aspect of a computer, it is both delicate and difficult for anyone other than a professional to manipulate. The registry contains everything from the configuration of the computer to the drivers and software that have been installed, as well as personal user preferences determined by each individual who logs on to that specific PC. If the Windows registry happens to fail, the computer will begin to run extremely slowly, if at all. Its operation will become unstable and difficult to manage, which can in turn lead to the loss of information stored on that computer's hard drive.

The registry, therefore, should be periodically cleaned to help prevent such loss. In order to clean or repair the registry, specialized programs, which contain the tools necessary for registry adjustment, would be needed. Correcting or editing the registry is usually best left to professionals, as they have been trained to recognize and work with the keys and values found within the registry.

These keys and values are the basic elements of the registry itself. The make-up of these two elements is similar to the make-up of the Windows file system. The keys are akin to folders, whereas the values are equivalent to the files contained in said folders. In referencing the keys found in the registry, the same syntax as used with file path names in Windows is used, with backslashes () used to indicate the levels of organization of the keys and values that are being referenced.
E.g. HKEY_LOCAL_MACHINESYSTEMCurrentControlSetHardware Profiles

The registry is structured into five categories, all beginning with the prefix HKEY, as shown in the example above. The five categories, also referred to as 'hives', are as follows, with their associated abbreviations :

HKEY_CLASSES_ROOT (HKCR)
HKEY_CURRENT_USER (HKCU)
HKEY_LOCAL_MACHINE (HKLM)
HKEY_USERS (HKU)
HKEY_CURRENT_CONFIG (HKCC)


HKEY_CLASSES_ROOT
This particular aspect of the Windows registry contains the majority of the information needed in order for Windows simply to function at a basic level. It contains the file associations, registered applications, and OLE Objects Class IDs necessary in order to maintain this functionality. Any error in data entry in this part of the registry could lead to an overall system malfunction.

HKEY_CURRENT_USER
This part of the Windows registry contains the individual information pertinent to the user currently logged on to the system. It holds personal preferences such as adjustments to environment variables, e.g audio, desktop configuration, e.g background and icon placement, and associated printers, network connections, application preferences, etc. It also contains the computer's security levels as determined by the user.

HKEY_LOCAL_MACHINE
This category of the Windows registry contains the information about the specific computer used to run the operating system. Included in this section is information on the applications, drivers, and hardware found on the computer itself. It also contains the Windows local security database. Within this category can be found five separate sub-keys : HARDWARE, SAM, SECURITY, SOFTWARE, and SYSTEM.

HKEY_USERS
Within this section can be found the information on each separate user account currently existing on the computer. Two sub-keys found in this section are .DEFAULT and the information needed for the user who is currently logged on to the system. The .DEFAULT key is necessary for when a user logs on under a guest account or without a profile.

HKEY_CURRENT_CONFIG
The current configuration of a computer's system is found within this key. The information in this category is gathered only when a particular component of the system is actually running and is not permanently stored on the hard drive, but is rather regenerated when the system reboots. The information found here is a portion of the information stored in HKEY_LOCAL_MACHINESystem and HKEY_LOCAL_ MACHINESoftware.

It can be seen that the information found within these categories is essential to the functionality of a computer. A clean registry can prevent data loss and system malfunctions, and hopefully save the user from having to reinstall the Windows operating system because of a crash or corruption. A specialized application aimed at optimizing the Windows registry is therefore critical for maintaining the integrity of both the registry and the system overall.