What is a "registry?"
Most of Windows users hear about the Windows registry only when something goes wrong with it and you start facing problems while working on your computer. As soon as you're introduced to it, you want to know what registry is and why it is so important for your computer - mainly so the thing will stop giving you so many issues. This page aims to give you a brief overview of the Windows registry, its structure, function and why it is so important - part of it is for the non-techies, but there are a lot more details for those of you with some computer smarts. You will also learn about the causes of registry problems and how to deal with them.
An Overview of
Windows Registry
When you make any changes to your computer, such as
changing the system settings, installing and removing new programs, software
or hardware, or perform various tasks on your computer, such as browsing the
web or use an application, your Windows needs to remember the changes you've
made. This information is required so that Windows can load the changes when
the PC is started back up again. Instead of saving all these changes in
different files, Windows saves them to a single place - the "Windows
Registry" - to centralize all of the information.
Windows Registry Structure
Now for the technical stuff. The Windows registry has a
hierarchal database that comprises keys, subkeys and their values. It looks
quite similar to the folder structure that you see when you load things up
in the Windows Explorer. You can view the registry tree with the help of the
Registry Editor tool that comes with your Windows operating system. To
launch the tool, open Start menu, select Run, type regedit in the
Open box and then click the
OK button.
When the Registry Editor tool opens, you will see five
keys at the base of the registry hive. These are—HKEY_CLASSES_ROOT,
HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE (HKLM), HKEY_USERS, and
HKEY_CURRENT_CONFIG. These keys
are known as the root keys. The hives for each root key comprises different
type of configuration information.
HKEY_USERS:
Abbreviated as HKU, this key comprises information related to all
user profiles configured on your computer. This key also includes template
information to create new user profiles. This key is a real root key and the
information included HKEY_CURRENT_USER is referred from this key.
HKEY_LOCAL_MACHINE:
Abbreviated as HKLM, this is the second real root key. This key comprises
information related to hardware and software configured on your computer.
The remaining registry keys, HKEY_CLASSES_ROOT and HKEY_CURRENT_CONFIG refer
this key for the required information.
HKEY_CURRENT_USER: Abbreviated as HKCU, this key comprises the specific information about the user
that is currently logged on to your computer. This means that all settings
related to Control Panel, Desktop, and user folders are saved in this key.
HKCU refers HKEY_USERS\ Security_ID
for information.
HKEY_CLASSES_ROOT: Abbreviated as HKCR, this key comprises a lot of vital information that is essential for your Windows computer. This includes registration information of components, files associations, GUIDs, and context handlers. Earlier this key was just a shadow of HKEY_LOCAL_MACHINE\Software. Post Windows 2000, this key displays a merged view of HKEY_LOCAL_MACHINE \ Software \ Classes and HKEY_USERS \ _Classes. This means that this key is a merged view of both per-user and machine-wide keys. So, primarily this key comprises both default settings that are applicable to all configured users and customized settings that override the default settings and are applicable only to specific users.
HKEY_CURRENT_CONFIG: Abbreviated as HKCU, this key is refers
HKEY_LOCAL_MACHINE\System for information. This key contains the hardware
profile information that is loaded when you local Windows PC starts.
Windows Registry
Problems
After going through all the technical information given
above, the importance of registry on a Windows computer becomes quite clear.
When you install a new computer, registry contains just enough information
that is required to keep your PC functional. However, as you start using
your PC, more and more information is added, modified, and removed from it.
Information is usually added and modified when you
install new programs, access the Internet, and modify your system's
configuration. Entries are removed when you perform tasks, such as
uninstalling programs and deleting a particular system or application
settings. All this new information causes the registry to grow continuously.
Registry problems usually start when the registry
database starts getting filled up with entries that are not actually
required. These include:
·
Duplicate and outdated
entries that generate when you reinstall, update or upgrade software and
device drivers installed on your computer.
·
Orphaned and empty registry
entries left behind due to incorrect or incomplete program removal.
·
Malicious entries added by
malicious programs, such as viruses, Trojans, worms, adware and spyware.
·
Buggy entries added by faulty
and incompatible programs and device drivers.
·
Corrupt entries, which are
usually a result of system and application crashes.
All this undesired information causes the registry to
bloat up at an unwarranted rate and eventually to get damaged, corrupt, and
fragmented. These issues cause the registry to slow down and also generate
several computer errors, such as DLL errors, runtime errors, and driver
errors.
Methods to Fix
Registry Problems
A certain amount of registry maintenance can be done with
the help of the Registry Editor (regedit) tool discussed above. However,
most of the tasks using this tool are done manually. Because the structure
of the registry is quite complex, this task is usually not easy, even for
many computer experts. Also, because the changes need to be done manually,
the chances of you making a mistake is quite high. The most problematic part
of the entire process is that Registry Editor does not have an undo option.
So, any changes that you've made are permanent. The only way to undo these
changes is by reverting them manually or restoring the registry from a
backup taken earlier.
Another and more popular method to perform registry
maintenance is by using a good registry cleaning tool. Registry cleaners are
third-party tools that are readily available on the Internet. An efficient
registry tool makes it possible for you to automatically scan the registry
for several types of problems and fix them. The scanning process is usually
safe because most registry tools make an automatic backup of the registry
before making any changes to it. Many registry tools also help compress and
reindex the registry by defragging it. This further helps in enhancing the
performance of your computer.
Return to the Registry Cleaners Guide