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. 

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 
• 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.

Windows Registry repair sounds daunting and difficult, but it is easy if you have the proper tools for the job.

Is your computer experiencing the following symptoms?

Sluggish Performance
Lots of Error Messages
Freezes
Crashes
The "Blue Screen Of Death"
Slow Bootups

If the answer is yes, there may be errors and invalid entries in your Windows registry, a filing system for settings and preferences related to software, hardware, and the operating system itself. The registry is like the central nervous system of your computer, and if it is compromised your computer will experience any number of annoying problems. Fortunately you do not need to be a computer technician to fix these disturbances.

Three easy steps to follow:

First of all, before you perform any sort of Windows registry repair, you will definitely want to make a new Windows restore point and a backup of the registry. This way, if any damages occur while you are cleaning it, you will be able to revert back to where you started.

1.) First, go to Start - All Programs - Accessories - System Tools - System Restore. Click the option to create a new restore point, name it, and then click create. This will make sure you have an up-to-date restore point for your operating system.

2.) Second, go to Start - Run, and then type in REGEDIT. This will open the registry editor. Don't touch anything! Messing with the registry can be dangerous if you don't know exactly what you're doing. Go to File - Export, and then pick a place to save your .reg file. Name your file (maybe something with the date in it), and click save. This creates a file with all the vital information in it should you need to revert back.

3.) Now that you have the proper safety backups in place, you can now proceed to the Windows  registry repair itself. The best way to do this is to use a specialized software program, such as RegCure. These programs will perform a deep scan and find corrupted, broken, and empty files and allow you to delete them. These programs will also allow you to make backups and repair any fixes that you have performed that you need to undo.

Make sure you use a reputable program for the job, since some are not as good as others. A few top programs are RegCure by ParetoLogic, and Registry Mechanic by PCTools.