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The Windows System Registry

What Is a Windows System Registry?
The system registry is one of the most important parts of a Windows-based computer system. Not to be tampered with lightly, the registry is a system-defined database used by the Windows operating system to store configuration information. Most Windows applications write data to the registry during installation,
and system components store and retrieve configuration data through the registry. The data stored in the registry varies according to the version of Microsoft Windows.

Registry Structure: The Tree, Nodes and Keys
The data is stored in the registry in a tree structure format, for those who have never opened the Registry Editor, you'd find its layout is similar to what you would see when you open your Windows Explorer. Each node within the registry tree contains a key which may have  both subkeys and data entries (called values). Depending on the application you run, the application may need only the associated key while others may need the value data set for that specific key. A hive in the registry is a group of keys, subkeys, and values in the registry that has a set of supporting files containing backups of its data. The Windows boot process automatically retrieves data from these supporting files.

[ Click to Enlarge Screenshot from Registry Editor ]

Key Terms To Understanding the Windows System Registry.

registry
A database used by the Windows operating system to store configuration information. The Registry consists of the following major sections...

Microsoft Windows
A family of operating systems for personal computers. Windows provides a graphical user interface (GUI), virtual memory management, multitasking, and support for many peripheral devices.

More Related Terms
tree structure
node
software
Windows XP

drivers

How Applications Use the Registry
Applications use the registry in several ways. They can add data to your registry by creating or opening existing keys. When applications add to the registry, the data is sorted by computer-specific data or user-specific data. Through this distinction applications can support multiple users and locate user profile data. An application can close a key and write the data it contains into the registry and applications can delete a value from a key or delete a key. Applications can also save specific data, or parts of the system registry in a file to load that file into the registry which is common when large amounts of data is being handled, or when multiple entries are being added to the registry.

Problems Associated With The Registry
Users can experience computer problems caused by system registry errors for several reasons. Problems with the computer itself will usually occur because of invalid or missing keys in the Windows registry. Some signs of trouble include computer system crashes, stalls, or even a noticeably slower operating speed. Of course knowing what causes errors in your system registry can go a long way to avoiding registry problems in the future. In most cases, problems with your registry occur from user actions mainly involving the installation or removal of software and hardware on your computer. If you frequently install or uninstall programs, delete startup programs, change hardware and do not remove old drivers (or have corrupted hardware drivers), delete software which was not properly uninstalled, or have installed a program with embedded spyware on your computer, then you may experience problems with your Windows system registry.

Editing a Registry
You can edit the Registry directly by using the Registry Editor provided with the operating system. However you must take great care because causing errors in the Registry could disable your computer.  You should not edit registry data that does not belong to your application unless it is absolutely necessary. If there is an error in the registry, your system may not function properly. If this happens, you can restore the registry to the state it was in when you last started the computer successfully. Editing a registry can be a difficult task and you should read through the help files for your specific Windows operating system before giving any further thought to editing the registry yourself.

Registry Backup and Restore
Some versions of Windows operating systems such as Windows 98, will create a backup of your system registry for you everyday provided your computer was rebooted during that calendar day. Unfortunately, the problems you may wish to fix with a registry restore may be included in the most recent backup, so it is advisable to start making your own registry backups instead of relying on those generated by Windows. It is important to note that the process for backing up and restoring a registry will differ between versions of Windows, and you should search the Microsoft Web site for exact instructions pertaining to your version of Windows.

Windows ME and Windows XP make system restore a bit easier as both have a System Restore feature that securely stores data that can later be used to put your system back to a previous state when it was known to function correctly.

If your last restore point had problems — for example a virus or worm, you'll face the probability that this information will also be restored to your system. It is important to remember that achieving a good system registry restore is dependant on you having taken the proactive steps to creating a good, usable backup to restore from. It is also important to read help files and search the Microsoft online Knowledgebase for registry backup and restore information for the version of windows you are running.

Registry Cleaner and Restore Utilities
For many, the process of cleaning and restoring a system registry is made easy with the use of third-party software utilities. A simple Google Web search for registry cleaning utilities will provide you with a plethora of results. For the most part, all registry repair and cleaner utilities provide you with an easy way to create registry backups, clean out your registry, and repair problems with your Windows system registry — some will provide additional features, but those are the basics to look for. Once you have installed your registry cleaner of choice, you will then set-up the basic options offered by the software (such as directories to store logs, backups, choose between automatic repair or to see the checklist of problems and confirm repair of each item. The cleaner utility will check areas storing information related to custom controls, software locations, shared DLLs, Startup programs, add/remove programs, and more.

You will have an option to create a system registry backup from the current state before making any changes to your Windows system registry as recommended by the cleaning utility. It is very important to create this backup, just incase something goes wrong when problems in the registry are repaired.

If you've make the decision to use a registry cleaning and repair utility to fix existing problems with your Windows System registry, you'll find you don't necessarily have to clean your registry frequently. But since you have the utility on your system creating registry backups is easily done with just a few clicks and can save you from total reformats and loss or corruption of your system in the future.


 

Did You Know...
Even spyware can leave behind keys in your system registry that may not be removed by all anti-spyware software. This is why some pop-ups and other spyware activities will persist on your computer after a system reboot. The good news is that  "registry scanning" is a feature being included in many newer anti-spyware products.


Vangie 'Aurora' Beal
Writer, www.Webopedia.com Last updated: May 27, 2005


Related Links

Microsoft MSDN Library
This Microsoft knowledgebase section provides a complete overview of the Windows system registry.

Microsoft MSDN Library
How to back up, edit, and restore the registry in Windows 2000.

How to Restore the Windows Registry From a Backup
If your Windows software does not start or run correctly, then your Registry may be corrupted.  Before you reinstall Windows, and all of your programs, try restoring a previous version of the Windows Registry. The restore procedure differs for Windows 95 and Windows 98.

Taking Advantage of Windows XP's System Restore
The System Restore component of Windows XP is the biggest "undo" available for Windows.

Virtual Doctor
A community where experts and novices help each other solve computing problems.

2005 Registry Repair Software Review
TopTen Reviews offers an excellent comparison of the top Registry Repair Software products.

Innovative Solutions
Innovative Solutions is a leading developer of Windows software focusing especially on system utilities and entertainment software.

iolo technologies
iolo technologies, LLC designs, manufactures, and sells award-winning software that increases the performance of computers running Microsoft Windows.

Diagnose your PC - C|net Reviews
C|net does a side-by-side comparison of two popular Windows utilities.

TechBuilder: Clean The Windows Registry To Keep PCs Lean & Mean
This TechBuilder article describes how you can use a free, "crippleware" version of a Registry clean-up tool to identify content in need of removal from the Windows Registry.